CLEANUP: atomic: add HA_ATOMIC_INC/DEC for unit increments

Most ADD/SUB callers use them for a single unit (e.g. refcounts) and
it's a pain to always pass ",1". Let's add them to simplify the API.
However we currently don't add any return value. If needed in the future
better report zero/non-zero than a real value for the sake of efficiency
at the instruction level.
1 file changed