FindMPI: should use pkgconfig files
cmake's FindMPI uses a somewhat complex mechanism to determine how to build and link against MPI libraries. This mechanism does not look at pkgconfig files that are often present.
It treats MPI libraries special in this way; for other libraries, cmake is happy to look at pkgconfig files. I think FindMPI should look at pkgconfig for fallback information instead of querying mpicxx
etc, which might not work since there is no standard describing how mpicxx
should work, and different MPI implementations behave differently here.