Only display the no pool work message once if there are multiple waiters in hash_pop

cgminer.c

@@ -5495,7 +5495,10 @@ static struct work *hash_pop(void)
 			then.tv_sec = now.tv_sec + 5;
 			then.tv_nsec = now.tv_usec * 1000;
 			rc = pthread_cond_timedwait(&getq->cond, stgd_lock, &then);
-			if (rc) {
+			/* Check again for !no_work as multiple threads may be
+			 * waiting on this condition and another may set the
+			 * bool separately. */
+			if (rc && !no_work) {
 				applog(LOG_WARNING, "Waiting for work to be available from pools.");
 				no_work = true;
 			}