Hopefully fix some old audio playing during manual track skip w/o crossfade. Worst case was 1/5 second of audio from pcmbuflen bytes later than the playign position of the old track would play.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@9876 a1c6a512-1295-4272-9138-f99709370657

apps/pcmbuf.c

@@ -301,6 +301,7 @@ bool pcmbuf_crossfade_init(bool manual_skip)
     if (LOW_DATA(6) || !pcmbuf_is_crossfade_enabled() || low_latency_mode)
     {
         pcmbuf_boost(true);
+        pcmbuf_flush_fillpos();
         pcmbuf_flush = true;
         return false;
     }