Previously, RUSTDOCFLAGS would get overriden when bootstrap set
`RUSTDOCFLAGS` itself. Propagate the flag manually, using the same logic
as `RUSTFLAGS`.

This also extracts the logic into a helper function to make sure it's
the same.

…vocations.

Fix issue 38686.

(update: placated tidy.)

This avoids naming collisions, particularly on Windows where the
dynamic library variable is PATH and setting it causes the in-tree
`tidy` to take precedence over the HTML tidy used by compiletest.

Intended to piggy-back on output from existing build.print_step_timings setting.

On non-unix platforms, does not try to call `getrusage` (and does not attempt to
implement its own shim; that could be follow-on work, though its probably best
to not invest too much effort there, versus using separate dedicated tooling).

On unix platforms, calls libc::rusage and attempts to emit the subset of fields
that are supported on Linux and Mac OS X. Omits groups of related stats which
appear to be unsupported on the platform (due to them all remaining zero).

Adjusts output to compensate for Mac using bytes instead of kb (a well known
discrepancy on Mac OS X). However, so far I observe a lot of strange values
(orders of magnitude wrong) reported on Mac OS X in some cases, so I would not
trust this in that context currently.

Propagate RUSTDOCFLAGS in the environment when documenting

Previously, RUSTDOCFLAGS would get overriden when bootstrap set
`RUSTDOCFLAGS` itself. Propagate the flag manually, using the same logic
as `RUSTFLAGS`.

Fixes rust-lang#75256.

…-verbose-verbose, r=Mark-Simulacrum

rustbuild: print out env vars on verbose rustc invocations

Print out environment variables related to Rust on sufficiently verbose rustc invocations.

Output is filtered via heuristic of only printing environment variables whose keys start with "RUST" or "CARGO." This filtering is mostly motivated by my not caring to see e.g. "PATH" in my own output, though it is also motivated as a way to try to avoid printing out personal secrets like github keys that people might have stored in their environments for better or for worse, especially since build output is often pasted into bug reports or gists.

Fix rust-lang#38686.

<details>

<summary>Click here to see sample output</summary>

Sample output looks like:

```
...
      Fresh core v0.0.0 (/home/pnkfelix/Dev/Rust/rust.git/library/core)
rustc env[0]: "CARGO"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/bin/cargo"
rustc env[1]: "CARGO_CRATE_NAME"="core"
rustc env[2]: "CARGO_INCREMENTAL"="0"
rustc env[3]: "CARGO_MAKEFLAGS"="--jobserver-fds=5,6 -j --jobserver-auth=5,6 -j"
rustc env[4]: "CARGO_MANIFEST_DIR"="/home/pnkfelix/Dev/Rust/rust.git/library/core"
rustc env[5]: "CARGO_PKG_AUTHORS"="The Rust Project Developers"
rustc env[6]: "CARGO_PKG_DESCRIPTION"=""
rustc env[7]: "CARGO_PKG_HOMEPAGE"=""
rustc env[8]: "CARGO_PKG_LICENSE"=""
rustc env[9]: "CARGO_PKG_LICENSE_FILE"=""
rustc env[10]: "CARGO_PKG_NAME"="core"
rustc env[11]: "CARGO_PKG_REPOSITORY"=""
rustc env[12]: "CARGO_PKG_VERSION"="0.0.0"
rustc env[13]: "CARGO_PKG_VERSION_MAJOR"="0"
rustc env[14]: "CARGO_PKG_VERSION_MINOR"="0"
rustc env[15]: "CARGO_PKG_VERSION_PATCH"="0"
rustc env[16]: "CARGO_PKG_VERSION_PRE"=""
rustc env[17]: "CARGO_PROFILE_RELEASE_CODEGEN_UNITS"="256"
rustc env[18]: "CARGO_PROFILE_RELEASE_DEBUG"="0"
rustc env[19]: "CARGO_PROFILE_RELEASE_DEBUG_ASSERTIONS"="false"
rustc env[20]: "CARGO_TARGET_DIR"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0-std"
rustc env[21]: "RUSTBUILD_NATIVE_DIR"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/native"
rustc env[22]: "RUSTC"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/bootstrap/debug/rustc"
rustc env[23]: "RUSTC_BOOTSTRAP"="1"
rustc env[24]: "RUSTC_BREAK_ON_ICE"="1"
rustc env[25]: "RUSTC_ERROR_METADATA_DST"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/tmp/extended-error-metadata"
rustc env[26]: "RUSTC_FORCE_UNSTABLE"="1"
rustc env[27]: "RUSTC_INSTALL_BINDIR"="bin"
rustc env[28]: "RUSTC_LIBDIR"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/lib"
rustc env[29]: "RUSTC_LINT_FLAGS"="-Wrust_2018_idioms -Wunused_lifetimes -Dwarnings"
rustc env[30]: "RUSTC_PRINT_STEP_TIMINGS"="1"
rustc env[31]: "RUSTC_REAL"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/bin/rustc"
rustc env[32]: "RUSTC_SNAPSHOT"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/bin/rustc"
rustc env[33]: "RUSTC_SNAPSHOT_LIBDIR"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/lib"
rustc env[34]: "RUSTC_STAGE"="0"
rustc env[35]: "RUSTC_SYSROOT"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0-sysroot"
rustc env[36]: "RUSTC_VERBOSE"="2"
rustc env[37]: "RUSTDOC"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/bootstrap/debug/rustdoc"
rustc env[38]: "RUSTDOCFLAGS"="--cfg=bootstrap -Dwarnings -Winvalid_codeblock_attributes --crate-version 1.52.0-dev"
rustc env[39]: "RUSTDOC_REAL"="/path/to/nowhere/rustdoc/not/required"
rustc env[40]: "RUSTFLAGS"="--cfg=bootstrap -Zmacro-backtrace -Clink-args=-Wl,-rpath,$ORIGIN/../lib -Cprefer-dynamic"
rustc env[41]: "RUST_COMPILER_RT_ROOT"="/home/pnkfelix/Dev/Rust/rust.git/src/llvm-project/compiler-rt"
rustc env[42]: "RUST_TEST_THREADS"="128"
rustc working directory: /home/pnkfelix/Dev/Rust/rust.git
rustc command: "LD_LIBRARY_PATH"="/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/lib:/home/pnkfelix/Dev/Rust/rust.git/objdi\
r-default/build/x86_64-unknown-linux-gnu/stage0-std/release/deps:/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/lib" "/home\
/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0/bin/rustc" "--crate-name" "core" "--edition=2018" "library/core/src/lib.rs" "--er\
ror-format=json" "--json=diagnostic-rendered-ansi,artifacts" "--crate-type" "lib" "--emit=dep-info,metadata,link" "-C" "opt-level=3" "-C" "embed-bitcode=no" "-C" \
"codegen-units=256" "-C" "debuginfo=0" "-C" "metadata=6748933694d8be19" "-C" "extra-filename=-6748933694d8be19" "--out-dir" "/home/pnkfelix/Dev/Rust/rust.git/objd\
ir-default/build/x86_64-unknown-linux-gnu/stage0-std/x86_64-unknown-linux-gnu/release/deps" "--target" "x86_64-unknown-linux-gnu" "-L" "dependency=/home/pnkfelix/\
Dev/Rust/rust.git/objdir-default/build/x86_64-unknown-linux-gnu/stage0-std/x86_64-unknown-linux-gnu/release/deps" "-L" "dependency=/home/pnkfelix/Dev/Rust/rust.gi\
t/objdir-default/build/x86_64-unknown-linux-gnu/stage0-std/release/deps" "--cfg=bootstrap" "-Zmacro-backtrace" "-Clink-args=-Wl,-rpath,$ORIGIN/../lib" "-Cprefer-d\
ynamic" "-Z" "binary-dep-depinfo" "-Wrust_2018_idioms" "-Wunused_lifetimes" "-Dwarnings" "--sysroot" "/home/pnkfelix/Dev/Rust/rust.git/objdir-default/build/x86_64\
-unknown-linux-gnu/stage0-sysroot" "-Z" "force-unstable-if-unmarked"
...
```

Rename the `tidy` binary to `rust-tidy`

This avoids naming collisions, particularly on Windows where the
dynamic library variable is PATH and setting it causes the in-tree
`tidy` to take precedence over the HTML tidy used by compiletest.

This doesn't change the x.py interface in any way, it still accepts `x.py test tidy` and prints error messages about `tidy`. It only changes the name of the file on disk.

Fixes rust-lang#82501.

…yn514

Add GUI tests

The start of a lot more of GUI tests! \o/

One test is to ensure that the search input can always be selected in all rustdoc "modes" (mobile, tablet mostly) whereas the second checks the shortcuts.

r? `@jyn514`

…e, r=Mark-Simulacrum

Add `build.print_step_rusage` to config.toml

Adds `build.print_step_rusage` to config.toml, which is meant to be an easy way to let compiler developers get feedback on the terminal during bootstrap about resource usage during each step.

The output is piggy-backed on `[PRINT-STEP-TIMINGS]`, mostly because the functionality seemed to naturally fit there in the overall control-flow and output structure (even if very little is shared between the implementations themselves).

Some sample output (from my Linux box, where I believe the `max rss` output to be somewhat trust-worthy...):

```
[...]
   Compiling regex v1.4.3
[RUSTC-TIMING] tempfile test:false 0.323 user: 1.418662 sys: 0.81767 max rss (kb): 182084 page reclaims: 26615 page faults: 0 fs block inputs: 0 fs block outputs: 2160 voluntary ctxt switches: 798 involuntary ctxt switches: 131
   Completed tempfile v3.1.0 in 0.3s
[RUSTC-TIMING] chalk_ir test:false 1.890 user: 1.893603 sys: 0.99663 max rss (kb): 239432 page reclaims: 32107 page faults: 0 fs block inputs: 0 fs block outputs: 25008 voluntary ctxt switches: 108 involuntary ctxt switches: 183
   Completed chalk-ir v0.55.0 in 1.9s
   Compiling rustc_data_structures v0.0.0 (/home/pnkfelix/Dev/Rust/rust.git/compiler/rustc_data_structures)
[RUSTC-TIMING] chrono test:false 1.244 user: 3.333198 sys: 0.134963 max rss (kb): 246612 page reclaims: 44857 page faults: 0 fs block inputs: 0 fs block outputs: 11704 voluntary ctxt switches: 1043 involuntary ctxt switches: 326
   Completed chrono v0.4.15 in 1.3s
[RUSTC-TIMING] rustc_rayon test:false 1.332 user: 1.763912 sys: 0.75996 max rss (kb): 239076 page reclaims: 35285 page faults: 0 fs block inputs: 0 fs block outputs: 19576 voluntary ctxt switches: 359 involuntary ctxt switches: 168
   Completed rustc-rayon v0.3.0 in 1.3s
   Compiling matchers v0.0.1
[RUSTC-TIMING] matchers test:false 0.100 user: 0.94495 sys: 0.15119 max rss (kb): 140076 page reclaims: 8200 page faults: 0 fs block inputs: 0 fs block outputs: 392 voluntary ctxt switches: 43 involuntary ctxt switches: 12
   Completed matchers v0.0.1 in 0.1s
[...]
```

fix env var name in CI

There no `SKIP_JOBS` env var name, only `SKIP_JOB`.

…lacrum

Propagate `--test-args` for `x.py test src/tools/cargo`

Fixes rust-lang#82621.

Try to clarify GlobalAlloc::realloc documentation comment.

This PR tries to improve the documentation of [GlobalAlloc::realloc](https://doc.rust-lang.org/alloc/alloc/trait.GlobalAlloc.html#method.realloc) with two aspects:

1. Explicitly mention that `realloc` preserves the contents of the original memory block.
2. Explicitly mention which layout should be used to deallocate the reallocated block.

…e-doc, r=petrochenkov

Fix a typo in the `find_anon_type` doc

…chenkov

Add more proc-macro attribute tests

r? `@petrochenkov`