PROTON-693: Fix for windows build

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1626861 13f79535-47bb-0310-9956-ffa450edef68
PROTON-694: split conversion and encoding during outbound transformation to allow calling separately

Applied patch from Clebert Suconic

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1626868 13f79535-47bb-0310-9956-ffa450edef68