Use xine's os_types.h file.
Define MPC_LITTLE_ENDIAN when needed.

Index: libmpcdec/mpcdec/config_types.h
===================================================================
--- libmpcdec.orig/mpcdec/config_types.h
+++ libmpcdec/mpcdec/config_types.h
@@ -35,7 +35,11 @@
 #ifndef __MUSEPACK_CONFIG_TYPES_H__
 #define __MUSEPACK_CONFIG_TYPES_H__
 
-#include <inttypes.h>
+#include "os_types.h"
+
+#ifndef WORDS_BIGENDIAN
+# define MPC_LITTLE_ENDIAN
+#endif
 
 typedef unsigned char mpc_bool_t;
 #define TRUE  1