Protect the build against homebrew's formula's upgrades

[TotoGaz]

When homebrew upgrades his openmpi forumula, our build breaks.

In the .travis.yml file the line ln -s /usr/local/Cellar/open-mpi/4.0.1_2 /usr/local/Cellar/open-mpi/4.0.1_1; reflects this issue.

We shall bring a short term (it's not working currently) and long term answers.

[TotoGaz]

It shall be noticed that our version of hdf5 (i.e. 1.10.3) does not compile with MPI 3 https://travis-ci.com/GEOSX/thirdPartyLibs/jobs/248025126.

I do not figure how it was working with open-mpi 4.0.1 however...

[TotoGaz]

Hi @rrsettgast!

hdf5 1.10.3 does not build against open-mpi 4.0.2. But is is OK for version 1.10.5 (see https://travis-ci.com/GEOSX/thirdPartyLibs/jobs/248083327). We are lucky on this.

I could also test the GEOSX's osx build against this new env (https://travis-ci.com/GEOSX/GEOSX/jobs/248096087) and it is succesful.

Is there any additional tests to run when changing a TPL version?

BTW, I only use the TRAVIS_BUILD_NUMBER to identify the tarball in ther GCP bucket.
I can make some modifications in this PR if you want (maybe adding the PR number of the 3rd party libraries repository would help?).

I still need to commit hdf5 v1.10.5 in tplMirror (removing 1.10.3) and I guess we're OK.
Unfortunately, I do not think we would be on tracks again before tonight...

[TotoGaz]

Hello @rrsettgast, GEOS-DEV/thirdPartyLibs#73 was able to build and push the TPL for OSX and #610 was able to retrieve the TPL for OSX.

I guess they could be reviewed (and merged if OK) so the CI/CD process is working again.

[TotoGaz]

The diff https://github.com/Homebrew/homebrew-core/pull/45466/files shows that some compatibility flag was removed in 4.0.2. Probably this is why we could build against 4.0.1 versions.