x.json2.decoder2: use json_str and json_len, intead of just json

vlib/time/parse.c.v

@@ -129,6 +129,7 @@ fn check_and_extract_date(s string) !(int, int, int) {
 // parse_rfc3339 returns the time from a date string in RFC 3339 datetime format.
 // See also https://ijmacd.github.io/rfc3339-iso8601/ for a visual reference of
 // the differences between ISO-8601 and RFC 3339.
+@[direct_array_access]
 pub fn parse_rfc3339(s string) !Time {
 	if s == '' {
 		return error_invalid_time(0, 'datetime string is empty')