Make opt_frame_pix_fmt() call show_pix_fmts() if the provided option

is "list".

Originally committed as revision 21628 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffmpeg.c

@@ -2605,7 +2605,7 @@ static void opt_frame_pix_fmt(const char *arg)
             av_exit(1);
         }
     } else {
-        list_fmts(avcodec_pix_fmt_string, PIX_FMT_NB);
+        show_pix_fmts();
         av_exit(0);
     }
 }