Function wait

test/pthread/test_pthread_clock_drift.c:17–22

volatile double mainThreadTime;

void wait(volatile int *address) {
  int state = emscripten_atomic_load_u32((void*)address);
  while (state == 0) {
    state = emscripten_atomic_load_u32((void*)address);
  }
}

void wake(volatile int *address) {
  emscripten_atomic_store_u32((void*)address, 1);