cad/NASTRAN-95: Fix hardcoded FC and FFLAG flags in patch

Given how patch-um_Makefile was constructed correctly with configure
variables, I suspect the similar-but-incorrect patch-sb_Makefile was
simply regenerated after configure was run. Let's replace the hardcoded
gfortran48 and it's flags with %%FC%% and %%FFLAGS%% so NASTRAN-95 builds
on other fortran compilers.

Approved by: Just-Fix-It