tools: Add atomic_test_and_set_bit()

tools: Add atomic_test_and_set_bit()

Add x86 and generic implementations of atomic_test_and_set_bit() to allow
KVM selftests to atomically manage bitmaps.

Note, the generic version is taken from arch_test_and_set_bit() as of
commit 415d83249709 ("locking/atomic: Make test_and_*_bit() ordered on
failure").

Signed-off-by: Peter Gonda <[email protected]>
Co-developed-by: Sean Christopherson <[email protected]>
Signed-off-by: Sean Christopherson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]