New RE_PROBE_IPV6_ONLY with better complexity in worst case

[AlekseyLobanov]

I found that RE_PROBE_IPV6_ONLY may have awful complexity (exponential) on some cases like ':'*100.

Fix included, tests are green.

[AlekseyLobanov]

Also three Regular Expressions may have cubic (N^3) complexity on some examples and I unable to perform quick fix.
What do you think about using RE2 library? It is still really fast but also will be fast on this examples.

[AlekseyLobanov]

As a POC I tried

traceroute6 to turner-tls.map.fastly.net (2a04:4e42:200::323) from 2600:1700:bab0:d40:985:f00a:98bd:f142, 5 hops max, 12 byte packets
 1  * * *
 2  :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::  27.635 ms  20.383 ms  23.438 ms
 3  * * *
 4  2001:1890:ff:ff08:12:242:117:16  20.118 ms  20.327 ms  21.213 ms
 5  * * *

at the web demo

[kellyjonbrazil]

Thanks for this fix! I don't want to introduce any new dependencies, so we'll have to pass on RE2.