add symlink for Arlequin commands + fix sanity check commands

[boegel]

(created using eb --new-pr)

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
node2526.golett.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz (haswell), Python 2.7.5
See https://gist.github.com/e6fd6c8086717fcd3947d51cb8b48a11 for a full test report.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
generoso - Linux centos linux 7.6.1810, x86_64, Intel(R) Xeon(R) CPU E5-2660 v4 @ 2.00GHz, Python 3.6.8
See https://gist.github.com/a7498bf8b4a2d626d306fe8cf993cb18 for a full test report.

[verdurin]

Test report by @verdurin
FAILED
Build succeeded for 0 out of 1 (1 easyconfigs in this PR)
easybuild.novalocal - Linux centos linux 7.8.2003, Intel Xeon Processor (Skylake, IBRS), Python 2.7.5
See https://gist.github.com/f1faf52ddaa68c7050b76670031358db for a full test report.

[verdurin]

Test report by @verdurin
FAILED
Build succeeded for 0 out of 1 (1 easyconfigs in this PR)
easybuild.novalocal - Linux centos linux 7.8.2003, Intel Xeon Processor (Skylake, IBRS), Python 2.7.5
See https://gist.github.com/99d298b061f8611717edfb9ab103f5d1 for a full test report.

[verdurin]

@boegel It's complaining it can't find the patch, which is odd.

[smoors]

Test report by @smoors
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
node318.hydra.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz (skylake_avx512), Python 2.7.5
See https://gist.github.com/d9eb0162fad521baf887a85c2143381e for a full test report.

[smoors]

@verdurin the patches (and the easyconfig) were added only recently, so probably not in the 4.2.0 release yet.
maybe it's better to test with an up to date develop version?

[smoors]

lgtm

[smoors]

Going in, thanks @boegel!