Update documentation of show_version() to account for latest changes.

patch by Stefano Sabatini, stefano.sabatini-lala poste it

Originally committed as revision 13463 to svn://svn.ffmpeg.org/ffmpeg/trunk

cmdutils.h

@@ -116,7 +116,6 @@ void show_banner(const char *program_name, int program_birth_year);
  * Prints the version of the program to stdout. The version message
  * depends on the current versions of the repository and of the libav*
  * libraries.
- * @param program_name name of the program
  */
 void show_version(void);