require QXMPP_LIBRARY to be found for FindQXMPP to succeed
Merge pull request #3276 from birarda/qxmpp-fix

require QXMPP_LIBRARY to be found for FindQXMPP to succeed
Merge branch 'master' of https://github.com/highfidelity/hifi into oculus-dk2
look for atls not atl in FindATL