lavu/opt: add av_opt_set_dict2() function

Existing av_opt_set_dict doesn't accept flags.
It doesn't allow to pass options to nested structs.
New function alllows that.

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>

libavutil/opt.h

@@ -541,6 +541,24 @@ int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name)
  */
 int av_opt_set_dict(void *obj, struct AVDictionary **options);
 
+
+/**
+ * Set all the options from a given dictionary on an object.
+ *
+ * @param obj a struct whose first element is a pointer to AVClass
+ * @param options options to process. This dictionary will be freed and replaced
+ *                by a new one containing all options not found in obj.
+ *                Of course this new dictionary needs to be freed by caller
+ *                with av_dict_free().
+ * @param search_flags A combination of AV_OPT_SEARCH_*.
+ *
+ * @return 0 on success, a negative AVERROR if some option was found in obj,
+ *         but could not be set.
+ *
+ * @see av_dict_copy()
+ */
+int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
+
 /**
  * Extract a key-value pair from the beginning of a string.
  *