use enum type instead of int

Originally committed as revision 13089 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/matroskadec.c

@@ -58,7 +58,7 @@ typedef struct Track {
     MatroskaTrackFlags flags;
 
     int encoding_scope;
-    int encoding_algo;
+    MatroskaTrackEncodingCompAlgo encoding_algo;
     uint8_t *encoding_settings;
     int encoding_settings_len;
 } MatroskaTrack;