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.

src/libcore/slice/mod.rs

@@ -5420,7 +5420,7 @@ macro_rules! impl_marker_for {
 }
 
 impl_marker_for!(BytewiseEquality,
-                 u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
+                 u8 i8 u16 i16 u32 i32 u64 i64 u128 i128 usize isize char bool);
 
 #[doc(hidden)]
 unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {