Meta-issue to track the readiness of the build system rollup

This is a meta-issue to track the readiness to merge the following pull requests, all related to synchronizing the build system across modules (aka. support-building-with-DUNE-2.3):

* opm/opm-material#10
* opm/dune-cornerpoint#41
* opm/opm-porsol#63
* opm/opm-upscaling#71
* opm/opm-benchmarks#20
* opm/opm-polymer#30
* opm/opm-autodiff#23
* opm/opm-verteq#27 

When ***this*** issue is closed they are deemed to be ready and will be merged shortly and without further warning.

Currently however, the following pull requests are slated for inclusion and pending review:

* opm/opm-core#326 "Fix SuperLU and Quadmath"
* opm/opm-core#329 "Support defining unquoted variables for config.h"
* opm/opm-core#330 "Simplify creation of Fortran function wrappers"

And if and only if these issues gets ready quickly (read: over the weekend), they *may* be included (but I don't want them to hold the train):

* opm/opm-core#334 "Include system information when building on MacOS X"
* opm/opm-core#335 "Support multi-lib installation"

If anyone sits on further improvements (to the build system), they are encourage to bring them forward now and add them to this list, so that we don't have to spend more time on this again before the release. (There certainly won't be more rollups from me).