Bug 1072294 - Build more files in content/media/mp4 in unified mode; r=cpearce

content/media/fmp4/moz.build

@@ -12,11 +12,11 @@ EXPORTS += [
 
 UNIFIED_SOURCES += [
     'BlankDecoderModule.cpp',
+    'MP4Decoder.cpp',
     'PlatformDecoderModule.cpp',
 ]
 
 SOURCES += [
-    'MP4Decoder.cpp',
     'MP4Reader.cpp',
 ]