q.go handle the Truncated can be better

[NewRegin]

in q.go(line 347 and below), if the err is dns.ErrTruncated will end this search and continue the
next one, but we want't this happen, so we can solve the problem of Truncated by the follow way:

//line [347]
....... switch e {
............... case nil:
............... ............//do nothing
............... case dns.ErrTruncated:
............... ............if *fallback {
............... ............... goto Redo
............... ............} else {
............... ............... .....goto Redo
............... ............}
........................fmt.Printf(";; Truncated\n")
............... default:
............... ........fmt.Printf(";; %s\n", e.Error())
............... ........continue
..............}

[miekg]

Ack, can you rework this into a PR?

[NewRegin]

my honor~