avtools: parse loglevel before all the other options.

This way it can be applied to cmdutils too -- e.g. showing the banner
and printing startup messages.

avconv.c

@@ -4019,6 +4019,7 @@ int main(int argc, char **argv)
     reset_options(&o);
 
     av_log_set_flags(AV_LOG_SKIP_REPEATED);
+    parse_loglevel(argc, argv, options);
 
     avcodec_register_all();
 #if CONFIG_AVDEVICE