flac: workaround for type inconsistency between new/old read callback

size_t (1.1.3) makes a lot more sense, but older flac used unsigned
here...

git-svn-id: https://svn.musicpd.org/mpd/trunk@5258 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/inputPlugins/flac_plugin.c

@@ -37,7 +37,7 @@
 
 static flac_read_status flacRead(const flac_decoder * flacDec,
                                   FLAC__byte buf[],
-				  unsigned *bytes,
+				  flac_read_status_size_t *bytes,
 				  void *fdata)
 {
 	FlacData *data = (FlacData *) fdata;