Old versions used char* for the data, new versions use int8_t*. They're often
not the same and differ in signedness.

(backported from 04199db2aeea966c2c879b1764427c87433570f1)

--- a/ext/timidity/gstwildmidi.c
+++ b/ext/timidity/gstwildmidi.c
@@ -631,7 +631,7 @@
   size = GST_BUFFER_SIZE (buffer);

   GST_OBJECT_LOCK (wildmidi);
-  bytes_read = WildMidi_GetOutput (wildmidi->song, (char *) data,
+  bytes_read = WildMidi_GetOutput (wildmidi->song, (gpointer *) data,
       (unsigned long int) size);
   GST_OBJECT_UNLOCK (wildmidi);