Auto merge of #134333 - daxpedda:stdarch-bump, r=daxpedda

Bump `stdarch`

This bumps `stdarch` to rust-lang/stdarch@684de0d to get in rust-lang/stdarch#1677 (tracked in rust-lang/rust#133908).

From the [commit history](rust-lang/stdarch@e5e00aa...684de0d) I deduced that there shouldn't be any changes to Rust necessary.

From past PRs I'm assuming that bumping `stdarch` like this is fine, but please let me know if this is somehow inappropriate or requires something more to be done!

try-job: arm-android
try-job: armhf-gnu

Author: bors