squash! fix watchdog performance

Author: bnoordhuis

ext/mini_racer_extension/mini_racer_extension.c

@@ -573,6 +573,8 @@ static void *v8_watchdog(void *arg)
     deadline = deadline_ms(c->timeout);
     pthread_mutex_lock(&c->wd.mtx);
     for (;;) {
+        if (c->wd.cancel)
+            break;
         pthread_cond_timedwait(&c->wd.cv, &c->wd.mtx, &deadline);
         if (c->wd.cancel)
             break;