[PATCH 08/13] atomics/arc: define atomic64_fetch_add_unless()

As a step towards unifying the atomic/atomic64/atomic_long APIs, this patch converts the arch/arc implementation of atomic64_add_unless() into an implementation of atomic64_fetch_add_unless(). A wrapper in will build atomic_add_unless() atop of this, provided it is given a preprocessor

[PATCH 08/13] atomics/arc: define atomic64_fetch_add_unless()

As a step towards unifying the atomic/atomic64/atomic_long APIs, this patch converts the arch/arc implementation of atomic64_add_unless() into an implementation of atomic64_fetch_add_unless(). A wrapper in will build atomic_add_unless() atop of this, provided it is given a preprocessor