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.

cmdutils.c

@@ -304,6 +304,41 @@ void parse_options(void *optctx, int argc, char **argv, const OptionDef *options
     }
 }
 
+/*
+ * Return index of option opt in argv or 0 if not found.
+ */
+static int locate_option(int argc, char **argv, const OptionDef *options, const char *optname)
+{
+    const OptionDef *po;
+    int i;
+
+    for (i = 1; i < argc; i++) {
+        const char *cur_opt = argv[i];
+
+        if (*cur_opt++ != '-')
+            continue;
+
+        po = find_option(options, cur_opt);
+        if (!po->name && cur_opt[0] == 'n' && cur_opt[1] == 'o')
+            po = find_option(options, cur_opt + 2);
+
+        if ((!po->name && !strcmp(cur_opt, optname)) ||
+             (po->name && !strcmp(optname, po->name)))
+            return i;
+
+        if (!po || po->flags & HAS_ARG)
+            i++;
+    }
+    return 0;
+}
+
+void parse_loglevel(int argc, char **argv, const OptionDef *options)
+{
+    int idx = locate_option(argc, argv, options, "loglevel");
+    if (idx && argv[idx + 1])
+        opt_loglevel("loglevel", argv[idx + 1]);
+}
+
 #define FLAGS (o->type == FF_OPT_TYPE_FLAGS) ? AV_DICT_APPEND : 0
 int opt_default(const char *opt, const char *arg)
 {