if X11 is not enabled (iOS or native OSX) make sure that any explicitly specified X11 libs are unset.
if X11 is not enabled (iOS or native OSX) make sure that any explicitly
specified X11 libs are unset.


git-svn-id: acec3fd5b7ea1eb9e79d6329d318e8118ee2e14f@44674 27541ba8-7e3a-0410-8455-c3a389f83636

bbockelm/root-historical,bbockelm/root-historical,bbockelm/root-historical,bbockelm/root-historical,bbockelm/root-historical,bbockelm/root-historical,bbockelm/root-historical