This only supports two addresses as the intended use is 1 IPv4 and 1 IPv6
address on a single-homed host, and the only supported configuration of
outgoing connections to other servers is to bind a single IPv4 or IPv6
address.
Charybdis requires C99 already, so it's high time we start using
stdbool. I've converted a few pieces of code already.
A lot of the old code that uses YES/NO should probably be updated too
because that's fucking hideous.
AC_LANG_PROGRAM needs to be quoted when used within AC_*_IFELSE:
https://lists.gnu.org/archive/html/bug-autoconf/2011-04/msg00017.html
This fixes the following warnings:
$ autoreconf
configure.ac:298: warning: AC_LANG_CONFTEST: no AC_LANG_SOURCE call detected in body
../../lib/autoconf/lang.m4:193: AC_LANG_CONFTEST is expanded from...
../../lib/autoconf/general.m4:2729: _AC_RUN_IFELSE is expanded from...
../../lib/m4sugar/m4sh.m4:639: AS_IF is expanded from...
../../lib/autoconf/general.m4:2748: AC_RUN_IFELSE is expanded from...
configure.ac:298: the top level
configure.ac:593: warning: AC_LANG_CONFTEST: no AC_LANG_SOURCE call detected in body
../../lib/autoconf/lang.m4:193: AC_LANG_CONFTEST is expanded from...
../../lib/autoconf/general.m4:2661: _AC_LINK_IFELSE is expanded from...
../../lib/autoconf/general.m4:2678: AC_LINK_IFELSE is expanded from...
configure.ac:593: the top level
...
configure.ac:309: warning: AC_LANG_CONFTEST: no AC_LANG_SOURCE call detected in body
../../lib/autoconf/lang.m4:193: AC_LANG_CONFTEST is expanded from...
../../lib/autoconf/general.m4:2729: _AC_RUN_IFELSE is expanded from...
../../lib/m4sugar/m4sh.m4:639: AS_IF is expanded from...
../../lib/autoconf/general.m4:2748: AC_RUN_IFELSE is expanded from...
configure.ac:309: the top level
...
