QPID-5111: Make library dependencies clearer in build system
- Use -as-needed to link libraries to avoid unnecessary libraries
- Tidyup mess with nss and qpid-proton libraries

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1519866 13f79535-47bb-0310-9956-ffa450edef68
QPID-5112: Simplify windows/non windows checks

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1519867 13f79535-47bb-0310-9956-ffa450edef68