UNSET_LOCK_HOLDER  664 gc/include/private/gc_locks.h #   define UNSET_LOCK_HOLDER() GC_lock_holder = NO_THREAD
UNSET_LOCK_HOLDER  690 gc/include/private/gc_locks.h #      define UNSET_LOCK_HOLDER()
UNSET_LOCK_HOLDER  701 gc/include/private/gc_locks.h #   define UNSET_LOCK_HOLDER()