nightly update

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@60276 65644016-39b1-43b1-bf79-96bc8fe82c15
Add check if IPv6 is supported by OS. 
Windows implementation is complete, while POSIX implementation should be reviewed and fixed if necessary.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@60277 65644016-39b1-43b1-bf79-96bc8fe82c15