Implement a var for containing the current year number rather than

hardcode it in the banner string.

Originally committed as revision 16678 to svn://svn.ffmpeg.org/ffmpeg/trunk

cmdutils.h

@@ -37,6 +37,8 @@ extern const char program_name[];
  */
 extern const int program_birth_year;
 
+extern const int this_year;
+
 extern const char **opt_names;
 extern AVCodecContext *avctx_opts[CODEC_TYPE_NB];
 extern AVFormatContext *avformat_opts;