[flang] Clip circular dependence between implementation modules (#85309)

flang/module/__fortran_type_info.mod uses __fortran_builtins.mod, but it
is also implicitly used when compiling __fortran_builtins.f90 (or
anything else). If __fortran_type_info.mod finds an old
__fortran_builtins.mod file, compilation can fail while building the new
one.

Break the dependence by *not* generating runtime derived type
information for __fortran_builtins.f90.