Fix zgossip errors/warnings on MSVC and missing DLL exports.
Merge pull request #510 from evoskuil/master

Fix zgossip errors/warnings on MSVC and missing DLL exports.
MSVC - emit debug symbols into debug static/ltcg libs.
Merge pull request #511 from evoskuil/master

MSVC - emit debug symbols into debug static/ltcg libs.
Merge branch 'master', remote-tracking branch 'upstream/master'