fix user data parsing code so it suppors pre1 and cvs

Originally committed as revision 4471 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h263.c

@@ -5759,17 +5759,15 @@ static int decode_user_data(MpegEncContext *s, GetBitContext *gb){
     }
     
     /* ffmpeg detection */
-    e=sscanf(buf, "FFmpeg%d.%d.%db%d", &ver, &ver2, &ver3, &build);
+    e=sscanf(buf, "FFmpe%*[^b]b%d", &build)+3;
     if(e!=4)
         e=sscanf(buf, "FFmpeg v%d.%d.%d / libavcodec build: %d", &ver, &ver2, &ver3, &build); 
     if(e!=4){
         if(strcmp(buf, "ffmpeg")==0){
-            s->ffmpeg_version= 0x000406;
             s->lavc_build= 4600;
         }
     }
     if(e==4){
-        s->ffmpeg_version= ver*256*256 + ver2*256 + ver3;
         s->lavc_build= build;
     }
     

libavcodec/mpegvideo.h

@@ -609,7 +609,6 @@ typedef struct MpegEncContext {
     int xvid_build;
     
     /* lavc specific stuff, used to workaround bugs in libavcodec */
-    int ffmpeg_version;
     int lavc_build;
     
     /* RV10 specific */