Function arena_nthreads_dec

deps/jemalloc/src/arena.c:1931–1934

}

void
arena_nthreads_dec(arena_t *arena, bool internal) {
	atomic_fetch_sub_u(&arena->nthreads[internal], 1, ATOMIC_RELAXED);
}

size_t
arena_extent_sn_next(arena_t *arena) {