Add stdarch bootstrap smoke test

[Kobzol]

I spent like two hours trying to reproduce the previous distcheck failure using the actual CI Docker image, but without luck. I wonder if it was a fluke..

try-job: x86_64-gnu-distcheck

[rustbot]

r? @Mark-Simulacrum

rustbot has assigned @Mark-Simulacrum.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[Kobzol]

@bors2 try

[rust-bors]

⌛ Trying commit 5e9bb04 with merge 3ec6b6c…

To cancel the try build, run the command @bors2 try cancel.

[rust-bors]

💔 Test failed

• CI ❌

[Kobzol]

Closing in favor of #143412.

[Kobzol]

Actually not, we might want to run core_arch tests anyway. Nevermind, reopening.

[rustbot]

⚠️ Warning ⚠️

• This PR is based on an upstream commit that is 21 days old.

  It's recommended to update your branch according to the rustc-dev-guide.

[Mark-Simulacrum]

@bors r+

[bors]

📌 Commit 5e9bb04 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[Kobzol]

Sorry, didn't get to this yet. Last time it failed in the distcheck job, I want to see if it's still bad to avoid wasting an auto build.

@bors r-

@bors try

[rust-bors]

⌛ Trying commit 5e9bb04 with merge 33666f0…

To cancel the try build, run the command @bors try cancel.

[rust-bors]

💔 Test failed (CI). Failed jobs:

• bors build finished (web logs, extended logs)
• try - x86_64-gnu-distcheck (web logs, extended logs)

[rust-log-analyzer]

The job x86_64-gnu-distcheck failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

##[endgroup]
[TIMING] core::build_steps::test::RustInstaller RustInstaller -- 94.370
Testing stdarch stage2 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
error: no matching package named `wasmprinter` found
location searched: crates.io index
required by package `stdarch-test v0.1.0 (/checkout/library/stdarch/crates/stdarch-test)`
As a reminder, you're using offline mode (--frozen) which can sometimes cause surprising resolution failures, if this error is too confusing you may wish to retry without `--frozen`.
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 1:41:39
make: *** [Makefile:49: check] Error 1
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 1:49:34
  local time: Sun Jul 27 16:06:48 UTC 2025
  network time: Sun, 27 Jul 2025 16:06:48 GMT
##[error]Process completed with exit code 1.
Post job cleanup.