merge changes from mpd-tree:

-use tree for tagTracker
-eliminate the master process

git-svn-id: https://svn.musicpd.org/mpd/trunk@4571 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/directory.c

@@ -173,6 +173,7 @@ int updateInit(int fd, List * pathList)
 	if (directory_updatePid == 0) {
 		/* child */
 		int dbUpdated = 0;
+		clearPlayerPid();
 
 		unblockSignals();