Rollup merge of #61724 - aschampion:128-bit-memcmp, r=sfackler
Rollup merge of #61724 - aschampion:128-bit-memcmp, r=sfackler

core: use memcmp optimization for 128 bit integer slices

All other sized integer slices do this. From #61665.

graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust