* "http://host:port/path?option1=val1&option2=val2...
*/
-static void url_add_option(char *buf, int buf_size, const char *fmt, ...)
+static av_printf_format(3, 4) void url_add_option(char *buf, int buf_size, const char *fmt, ...)
{
char buf1[1024];
va_list ap;