Instead of using the adhoc code for checking and including (globally!)
BLAS/LAPACKE, use PkgConfig to correctly identify libs (see deleted
comment: "Hope this gets fixed in future!" -- you are welcome). Next,
only link into those libraries that need it (PHY_UE, SIMU). Note that
only RHEL also needs cblas, so it is a non-REQUIREd dependency that is
only linked in if available. Further, take out linking into all other
modules, as they don't need it.

In the source code, take out preprocessor directives to correctly
include headers -- that is cmake's job, which it does just fine now.