rust: sync: atomic: Add i8/i16 xchg and cmpxchg support

Add atomic xchg and cmpxchg operation support for i8 and i16 types
with tests.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251228120546.1602275-4-fujita.tomonori@gmail.com
2 files changed