update OpenFOAM easyblock for changes in v2012

[furstj]

This patch resolves sanity check error with new OpenFOAM v2012 layout proposed in pr #11876.

Mpi related libraries are located in platform/..../eb-mpi rather than in platform/..../mpi.

Edit: requires EasyBlock changes in #2321

[olesenm]

I would argue that the it should probably always have been 'eb-mpi' or something like that the entire time. It is just a matter of how EasyBuild decided to patch the etc/config.sh/mpi file. Could have easily defined it there.

[Micket]

lgtm

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS OpenFOAM-6-foss-2019b.eb

Build succeeded for 1 out of 1 (1 easyconfigs in total)
node2602.swalot.os - Linux centos linux 7.9.2009, x86_64, Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz (haswell), Python 3.6.8
See https://gist.github.com/64f24a132d2fd53fd84bd31bb782cd0b for a full test report.

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS OpenFOAM-8-foss-2020a.eb

Build succeeded for 1 out of 1 (1 easyconfigs in total)
node3614.doduo.os - Linux RHEL 8.2, x86_64, AMD EPYC 7552 48-Core Processor (zen2), Python 3.6.8
See https://gist.github.com/e6292942fe5ed54b030de889c8f7ea78 for a full test report.

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS OpenFOAM-v1912-intel-2019b.eb

Build succeeded for 1 out of 1 (1 easyconfigs in total)
node3101.skitty.os - Linux centos linux 7.9.2009, x86_64, Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz, Python 3.6.8
See https://gist.github.com/9636623d9381513f9d38ea16a63b41b6 for a full test report.

[Micket]

Hm, how did you upload test report to easyblock prs? Anyway.. it worked fine for my as well so i think it's good to go.

[boegel]

@Micket Just combine --include-easyblocks-from-pr with --upload-test-report. If there's no --from-pr used, the test report goes to the easyblocks PR (see easybuilders/easybuild-framework#3446)