Auto merge of #57918 - Centril:rollup, r=Centril

Auto merge of #57918 - Centril:rollup, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #57407 (Stabilize extern_crate_self)
 - #57703 (Make MutexGuard's Debug implementation more useful.)
 - #57764 (Fix some minor warnings)
 - #57825 (un-deprecate mem::zeroed)
 - #57827 (Ignore aarch64 in simd-intrinsic-generic-reduction)
 - #57908 (resolve: Fix span arithmetics in the import conflict error)
 - #57913 (Change crate-visibility-modifier issue number in The Unstable Book)

Failed merges:

r? @ghost