fix Mako easyconfigs using a */2018* toolchain

[boegel]

partial fix for #10462

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 10 out of 10 (10 easyconfigs in this PR)
node2697.swalot.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz (haswell), Python 2.7.5
See https://gist.github.com/4c4bad05e99f30a9de00c0ef1cb50d19 for a full test report.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 10 out of 10 (10 easyconfigs in this PR)
node3402.kirlia.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) Gold 6240 CPU @ 2.60GHz (cascadelake), Python 2.7.5
See https://gist.github.com/93b18d9e09cd1dc74d7730df6b9591ad for a full test report.

[lexming]

Test report by @lexming
FAILED
Build succeeded for 6 out of 10 (10 easyconfigs in this PR)
node150.hydra.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) CPU E5-2680 v2 @ 2.80GHz, Python 2.7.5
See https://gist.github.com/b672340c54f8e19d5c7b6559db56387b for a full test report.

[lexming]

Several of our old Python installations are not up to date with changes in Easybuild, so I'll have to rebuild those before I can test this PR.

[lexming]

Test report by @lexming
SUCCESS
Build succeeded for 10 out of 10 (10 easyconfigs in this PR)
node150.hydra.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) CPU E5-2680 v2 @ 2.80GHz, Python 2.7.5
See https://gist.github.com/4845174e5d402f59276d8d79c5838e9c for a full test report.

[lexming]

LGTM

[lexming]

Going in, thanks @boegel !