[libc++] Add static_assert to make sure rate limiter doesn't use locks

We want to be sure that atomic<size_t> is always lock-free, or the code
will be much slower than expected (and could even conceivably fail if
the lock implementation somehow calls back into libc++abi).

GitOrigin-RevId: 16779f8084541b626578a4bda2f51ee741dcd7bf
1 file changed