Implement PIX_FMT_NE() macro.

Originally committed as revision 18131 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/pixfmt.h

@@ -112,6 +112,12 @@ enum PixelFormat {
     PIX_FMT_NB,        ///< number of pixel formats, DO NOT USE THIS if you want to link with shared libav* because the number of formats might differ between versions
 };
 
+#ifdef WORDS_BIGENDIAN
+#   define PIX_FMT_NE(name) PIX_FMT_##name##BE
+#else
+#   define PIX_FMT_NE(name) PIX_FMT_##name##LE
+#endif
+
 #ifdef WORDS_BIGENDIAN
 #define PIX_FMT_RGBA PIX_FMT_RGB32_1
 #define PIX_FMT_BGRA PIX_FMT_BGR32_1