This removes a version check for LLVM >=13, and specifies prefixes as a series
of independent `--check-prefix` flags instead of a single `--check-prefixes`.

Any flags specified here will be passed to LLVM's `filecheck` tool, in tests
that use that tool.

This makes room for migrating over `tests/run-make/instrument-coverage`,
without increasing the number of top-level items in the codegen test directory.

This test was already very close to being an ordinary codegen test, except that
it needed some extra logic to set a few variables based on (target) platform
characteristics.

Now that we have support for `//@ filecheck-flags:`, we can instead set those
variables using the normal test revisions mechanism.

This define was copied over from the run-make version of the test, but doesn't
seem to serve any useful purpose.

In `auxiliary/sigpipe-utils.rs`, all we want to know is the current
`SIGPIPE` disposition. We should not change it. So use `libc::sigaction`
instead of `libc::signal`. That way we can also remove the code that
restores it.

Fixes rust-lang#121503.
Fixes rust-lang#121597.

…wiser

Allow tests to specify a `//@ filecheck-flags:` header

This allows individual codegen/assembly/mir-opt tests to pass extra flags to the LLVM `filecheck` tool as needed.

---

The original motivation was noticing that `tests/run-make/instrument-coverage` was very close to being an ordinary codegen test, except that it needs some extra logic to set up platform-specific variables to be passed into filecheck.

I then saw the comment in `verify_with_filecheck` indicating that a `filecheck-flags` header might be useful for other purposes as well.

…e-identifier-types, r=fmease,Manishearth

Split Diagnostics for Uncommon Codepoints: Add Individual Identifier Types

This pull request further modifies the `uncommon_codepoints` lint, adding the individual identifier types of `Technical`, `Not_NFKC`, `Exclusion` and `Limited_Use` to the diagnostic message.

Example rendered diagnostic:
```
error: identifier contains a Unicode codepoint that is not used in normalized strings: 'ij'
  --> $DIR/lint-uncommon-codepoints.rs:6:4
   |
LL | fn dijkstra() {}
   |    ^^^^^^^
   = note: this character is included in the Not_NFKC Unicode general security profile
```

Second step of rust-lang#120228.

Don't unnecessarily change `SIGPIPE` disposition in `unix_sigpipe` tests

In `auxiliary/sigpipe-utils.rs`, all we want to know is the current `SIGPIPE` disposition. We should not change it. So use `libc::sigaction` instead of `libc::signal`. That way we can also remove the code that restores it.

Part of rust-lang#97889.

… r=notriddle

Correctly handle if rustdoc JS script hash changed

It's something that annoyed me for quite some time: I have nightly docs open (for both std and compiler). And often, I don't look at the page for some days. Then when I come back to it, I make a search... except nothing happens. Took me a while to figure out that it was because the hash of one of the JS files we load for the search (either `search.js` or `search-index.js`) was updated in the meantime, preventing the search to be done. To go around it, I added to press `ENTER` to make the form submitted (which would reload the same page but with the correct hashes this time and the search being run).

r? `@notriddle`

…allout, r=lcnr

Fix more rust-lang#121208 fallout (round 3)

rust-lang#121208 converted lots of delayed bugs to bugs. Unsurprisingly, there were a few invalid conversion found via fuzzing.

r? `@lcnr`