MFH: r546879

databases/grass7: fix build on 11i386

When I added the option for compiling with openmp, like other ports, I don't use compiler:openmp but directly the default compiler because it works just as well. However, on FreeBSD 11, grass only builds well with LLVM90.

While I'm here I added with-proj-[includes|libs] to be more thorough

Approved by: tcberner
Differential Revision: https://reviews.freebsd.org/D25712

Approved by: ports-secteam (joneum)