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.

avserver.c

@@ -4668,6 +4668,7 @@ int main(int argc, char **argv)
 {
     struct sigaction sigact;
 
+    parse_loglevel(argc, argv, options);
     av_register_all();
 
     show_banner();