various libX* easyconfigs w/ intel/2016a

[boegel]

wrapper PR for #2564, #2565, #2566 by @hajgato (Jenkins is having trouble with these for some reason...)

depends on #2549 and #2573

[hpcugentbot]

Easyconfigs unit test suite PASSed (see https://jenkins1.ugent.be/job/easybuild-easyconfigs-pr-builder/6692/console for more details).

This pull request is now ready for review/testing.

Please try and find someone who can tackle this; contact @boegel if you're not sure what to do.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 6 out of 6 (6 easyconfigs in this PR)
Linux centos linux 7.2.1511, Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz, Python 2.7.5
See https://gist.github.com/94f1125cf11286637083 for a full test report.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 6 out of 6 (6 easyconfigs in this PR)
Linux SL 6.7, Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz, Python 2.6.6
See https://gist.github.com/6a437ff3a7abf249c689 for a full test report.

[boegel]

reviewed via #2564, #2565, #2566, going in

Thanks @hajgato!