Add ifxetex and ifluatex to 'live' test suite

This is in preparation for a switch to the new build system: the only test
result that changes is the one listing loaded files.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@4799 de43f980-851b-0410-b2f7-c40aca1f87e0