More support for release workflow
- Add a matrix used for the deployment tests for tarballs.
- Make gromacs.py support builds with static linking, make it
possible to run the tests (including regression tests) with 'make
check', and do an install with a normal + mdrun-only build.
- Adapt the website build script to releng changes, and do not run all
the Doxygen targets twice for the website build.
Some TODOs in gromacs.py identify what would still be necessary to get
to the level the Test_Tarballs_* jobs currently do, but that can also be
improved separately. Now this, together with the releng changes,
produces something useful reasonably robustly.
Change-Id: Idca8974c5c9e2ee20e04f0a309e0f306a9c615d6