[Issue 19997] std.socket.InternetHost.getHostByAddr unittest does not work with IPv6

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19997

shove <shove at 163.com> changed:

           What    |Removed                     |Added
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                 CC|                            |shove at 163.com

--- Comment #1 from shove <shove at 163.com> ---
https://github.com/dlang/phobos/blob/35e9f2fbbaab75815c01a7e6b7d207e98afb9d56/std/socket.d#L986

Also here, IPv6 can cause exceptions.
std/socket.d does not fully support IPv6, such as GetHostByAddr().

Perfecting std/socket.d to fully support IPv6 is certainly the best, but it's a
bit of a workload.
So it may be a short-term solution to temporarily handle unittest to make it
work properly. Otherwise, auto-tester of PR will be interrupted frequently.

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