Install mp4ff_int_types.h for mythmusic.

http://bugs.gentoo.org/275008

--- common/mp4ff/Makefile.am
+++ common/mp4ff/Makefile.am
@@ -1,5 +1,5 @@
 lib_LTLIBRARIES = libmp4ff.la
-include_HEADERS = mp4ff.h mp4ffint.h
+include_HEADERS = mp4ff.h mp4ffint.h mp4ff_int_types.h
 
 AM_CFLAGS = -DUSE_TAGGING=1