Rollup merge of #93035 - Amanieu:stdarch_fix, r=Mark-Simulacrum

Fix stdarch submodule pointing to commit outside tree

PR #93016 was merged with the stdarch submodule pointing to a commit in
a PR branch and not in master. This was due to a circular dependency
between the rust and stdarch changes which would cause the other to fail
to build.

cc #75109