Modified configure.in to include some debug build option info at the end
of the scripts execution. Can be removed by release time.
Modified configure.in to include a --with-ipv6 option
Default build is without IPv6 support now to enable you need to use the
--with-ipv6 command line option to configure.
Modified plugins/utils.* to use USE_IPV6
git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@410 f882894a-f735-0410-b71e-b25c423dba1c
