ffmpeg: complain loudly and exit in case removed -sameq option is specified

This is better than silently ignoring the option, which results in
unexpected quality results.

ffmpeg_opt.c

@@ -159,8 +159,11 @@ static int opt_pad(void *optctx, const char *opt, const char *arg)
 
 static int opt_sameq(void *optctx, const char *opt, const char *arg)
 {
-    av_log(NULL, AV_LOG_WARNING, "Ignoring option '%s'\n", opt);
-    return 0;
+    av_log(NULL, AV_LOG_ERROR, "Option '%s' was removed. "
+           "If you are looking for an option to preserve the quality (which is not "
+           "what -%s was for), use -qscale 0 or an equivalent quality factor option.\n",
+           opt, opt);
+    return AVERROR(EINVAL);
 }
 
 static int opt_video_channel(void *optctx, const char *opt, const char *arg)