ao_coreaudio: use 0 as timeout for CFRunLoopRunInMode

Handle all pending events and exit instead of waiting. When there are lots of
input events (for example, scrolling with trackpad), timeout can add up
to make a huge frame delay. In my tests, if I scroll fast enough, that loop
would never exit.

audio/out/ao_coreaudio.c

@@ -1104,7 +1104,7 @@ static int play(void* output_samples,int num_bytes,int flags)
     audio_resume();
 
     do {
-        exit_reason = CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.01, true);
+        exit_reason = CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, true);
     } while (exit_reason == kCFRunLoopRunHandledSource);
 
     return wrote;