[Opm] Adjust CMake build defaults to reflect those of DUNE 2.8 more closely

[Markus Blatt]

Am Thu, Mar 03, 2022 at 11:14:44AM +0100 schrieb Markus Blatt:
> [...]
>Errors like this one are hard to judge for the average user (default USE_MPI=OFF):
>
>"
>-- This build defaults to installing in /home/mblatt/opt/opm
>CMake Error at /home/mblatt/src/dune/opm-master/opm-common/cmake/Modules/OpmSatellites.cmake:63 (add_executable):
>  Target "test_cartgrid" links to target "MPI::MPI_C" but the target was not
>  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
>  an ALIAS target is missing?
>Call Stack (most recent call first):
>  /home/mblatt/src/dune/opm-master/opm-common/cmake/Modules/OpmLibMain.cmake:248 (opm_compile_satellites)
>  CMakeLists.txt:119 (include)
>"
>
>this already appears in opm-common. I was not aware that we would already fail here. Makes this even more pressing.

Sorry. Actually this happens in opm-grid and not opm-common