hostname: Use more modern network APIs.
Reported by Jens Petersen <petersen@redhat.com>
at <https://savannah.gnu.org/bugs/?63983>.
* autogen.sh (GNULIB_MODULES_TOOLS_FOR_SRC): Add getaddrinfo.
* gettext-tools/src/hostname.c (HAVE_GETADDRINFO): Define to 1.
Do the #includes for gethostname() after those for getaddrinfo().
(ipv4_is_linklocal, ipv6_is_linklocal): New functions.
(print_hostname): For long_format and ip_format, prefer getaddrinfo over
gethostbyname.
* gettext-tools/src/Makefile.am (hostname_LDADD): New variable.
