output/osx: remove sleep call from render callback

Blocking inside the render callback is forbidden, and this sleep call
didn't make any sense.

src/output/osx_plugin.c

@@ -142,10 +142,6 @@ osx_render(void *vdata,
 
 	buffer->mDataByteSize = buffer_size;
 
-	if (!buffer_size) {
-		g_usleep(1000);
-	}
-
 	return 0;
 }