Avoid unnecessary Fortran checks

VELOCIraptor doesn't use Fortran, and therefore checking for a Fortran compiler and runtime libraries is not necessary. Furthermore this can introduce unnecessary problems; in my case it prevented me to compile SWIFT with VELOCIraptor in our local platform.

I suspect the appearance of these checks is a remnant from a potential copy-paste from the grackle integration checks appearing just before VELOCIraptor's.

Signed-off-by: Rodrigo Tobar rtobar@icrar.org