Added patch to make ipv6 life easier.

Added patch to make ipv6 life easier.

Copy of the patch notes:
[PATCH] friendlier ai_flag hints for ipv6 hosts

*) Do not use AI_ADDRCONFIG on listening sockets, because this flag
makes it impossible to explicitly listen on '127.0.0.1' if no global
ipv4 address is configured additionally, making this a very
uncomfortable option.
*) Add AI_V4MAPPED hint for connecting sockets for a similar purpose.

If your system is globally only connected via ipv6 you still want to be
able to use '127.0.0.1' and 'localhost'.
Specifically, PVE - unless explicitly asking for insecure mode - uses
loopback addresses with QEMU for live migrations tunneled over SSH.
These fail to start because AI_ADDRCONFIG makes getaddrinfo refuse to
work with '127.0.0.1'.

As for the AI_V4MAPPED flag the situation is similar.

I also want to point out that glibc explicitly sidesteps POSIX standards
when passing 0 as hints by then assuming both AI_V4MAPPED and
AI_ADDRCONFIG (the latter being a rather weird choice IMO), while
according to POSIX.1-2001 it should be assumed 0. (glibc considers its
choice an improvement.)
Since either AI_CANONNAME or AI_PASSIVE are passed in our cases, glibc's
default flags in turn are disabled again unless explicitly added, which
I do with this patch.