Brian Cunnie a2564c12d3 dig shouldn't bomb-out if forbidden hyphen is used ...

Yes, according to the RFC it shouldn't begin with a hyphen. And, since
we're on the topic, underscores were supposed to be off the table, too,
but Microsoft used them anyway, and you know what? We're gonna use the
"forbidden hyphen". And we're gonna instruct `dig` to not be so
persnickety.

fixes:
```
dig +short  AAAA api.--.sslip.io
dig: idn2_lookup_ul failed: string start/ends with forbidden hyphen
```

I had to make it work for old-style (e.g. macOS dig) which is version
"DiG 9.8.3-P1" as well as for the new version ("DiG
9.11.3-RedHat-9.11.3-6.fc28") which has this new
[library](https://www.gnu.org/software/libidn/libidn2/reference/libidn2-idn2.html)
which does the following:

> Perform IDNA2008 lookup string conversion on domain name src , as described in section 5 of RFC 5891

2018-05-23 20:03:34 -07:00

..

check-dns_spec.rb

dig shouldn't bomb-out if forbidden hyphen is used

2018-05-23 20:03:34 -07:00