Fixes rust-lang#68104

Previous, we were encoding AnonConst as a regular Const, causing us to
treat them differently after being deserialized in another compilation
session.

This will run all tests for `riscv64gc-unknown-linux-gnu` in a QEMU
instance. This is based upon the armhf QEMU test image.

Thanks to jfrimmel for pointing this out

Co-authored-by: J. Frimmel <31166235+jfrimmel@users.noreply.github.com>

The build is not actually needed often, and it can be added back on a
case-by-case basis if a specific PR needs access to it.

Insufficient sanitization of the x87 FPU tag word in the trusted enclave runtime allowed unprivileged adversaries in the containing host application to induce incoherent or unexpected results for ABI-compliant compiled enclave application code that uses the x87 FPU.

Vulnerability was disclosed to us by Fritz Alder, Jo Van Bulck, David Oswald and Frank Piessens

…r=varkor

Properly encode AnonConst into crate metadata

Fixes rust-lang#68104

Previous, we were encoding AnonConst as a regular Const, causing us to
treat them differently after being deserialized in another compilation
session.

Support sanitizers on aarch64-unknown-linux-gnu

RISC-V Emulated Testing

Adds a disabled docker image on which to run RISC-V tests. Based on the armhf image.

Test using
```
./src/ci/docker/run.sh riscv64gc-linux
```

cc: @msizanoen1

…ulacrum

Update CFGuard syntax

Update the naming and syntax of the control-flow-guard option, as discussed in rust-lang#68793.

r? @Mark-Simulacrum

…ark-Simulacrum

ci: disable alt build during try builds

The alt build is not actually needed often, and it can be added back on a case-by-case basis if a specific PR needs access to it.

This will free up a builder.

r? @Mark-Simulacrum

Emit line info for generator variants

Debuggers should be able to read a generator / async fn state machine and show the line it's suspended at. Eventually, this could grow into an "async stack trace" feature of sorts. While no debugger support this for Rust today, this PR adds the debuginfo necessary for that support to exist.

[This gist](https://gist.github.com/tmandry/6d7004fa008684f76809208847459f9b) shows the resulting debuginfo for a simple example. Here's a snippet:

```
0x00000986:           DW_TAG_variant
                        DW_AT_discr_value       (0x03)

0x00000988:             DW_TAG_member
                          DW_AT_name    ("3")
                          DW_AT_type    (0x000009bc "Suspend0")
                          DW_AT_decl_file       ("/home/tmandry/code/playground/generator-simple.rs")
                          DW_AT_decl_line       (6)
                          DW_AT_alignment       (8)
                          DW_AT_data_member_location    (0x00)
```

The file and line have been added here. The line currently points to the beginning of the statement containing the yield (or await), because that's what the MIR source info points to for the yield terminator. (We may want to point to the yield or await line specifically, but that can be done independently of this change.)

Debuggers don't know how to use this kind of info yet. However, we're hoping to experiment with adding such support to Fuchsia's debugger. It would be exciting if someone were interested in adding similar to support to gdb/lldb.

r? @oli-obk
cc @eddyb @jonas-schievink

Part of rust-lang#73524.

…jethrogb

Prevent attacker from manipulating FPU tag word used in SGX enclave

Insufficient sanitization of the x87 FPU tag word in the trusted enclave runtime allowed unprivileged adversaries in the containing host application to induce incoherent or unexpected results for ABI-compliant compiled enclave application code that uses the x87 FPU.

Vulnerability was disclosed to us by Fritz Alder, Jo Van Bulck, David Oswald and Frank Piessens

cc: @jethrogb