- Redocument memory ordering from "no ordering" to "acquire-release". (No
functional change: both LOCK WHATEVER on x86, and LDAXR/STLXR loops on ARM64,
already have this property.)
- Remove IncUnlessZeroInt32 and DecUnlessOneInt32, which were only faster than
the equivalent loops using sync/atomic before the Go compiler inlined
non-unsafe.Pointer atomics many releases ago.
PiperOrigin-RevId: 295811743