monitor: Abort inotify directory scanning on quit

Add more interruption point in case we receive a quit signal while we're
scanning a large directory.

monitor.c

@@ -527,7 +527,7 @@ monitor_insert_directory(int fd, char *name, const char * path)
 		DPRINTF(E_ERROR, L_INOTIFY, "opendir failed! [%s]\n", strerror(errno));
 		return -1;
 	}
-	while( (e = readdir(ds)) )
+	while( !quitting && (e = readdir(ds)) )
 	{
 		if( e->d_name[0] == '.' )
 			continue;
@@ -669,7 +669,7 @@ start_inotify(void)
 		}
 
 		i = 0;
-		while( i < length )
+		while( !quitting && i < length )
 		{
 			struct inotify_event * event = (struct inotify_event *) &buffer[i];
 			if( event->len )