Fix bug slowing down pgbench when -P is used.

A removed check in ba3deeef made all threads but the main one busy-loop
when -P was used. All threads computed the time to the next time the
progress report should be printed, but only the main thread did so and
re-scheduled it only for the future.

Reported-By: Jesper Pedersen
Discussion: 55C4E190.3050104@redhat.com

src/bin/pgbench/pgbench.c

@@ -3646,7 +3646,7 @@ threadRun(void *arg)
 		}
 
 		/* also wake up to print the next progress report on time */
-		if (progress && min_usec > 0)
+		if (progress && min_usec > 0 && thread->tid == 0)
 		{
 			/* get current time if needed */
 			if (now_usec == 0)