libgomp: Only check for 2*sizeof(void*) int type with Fortran [PR96661]

The depend type is a struct with two pointer members for C/C++ - but for
Fortran OpenMP requires an integer type with kind = omp_depend_kind. Thus,
libgomp's configure checks that an integer type/kind with size 2*sizeof(void*)
is available. However, this integer type/kind is not needed when building without
Fortran support. Thus, only check this when Fortran is enabled.

libgomp/
	PR libgomp/96661
	* configure.ac: Only check for int-type = 2*size_t support when
	building with Fortran support.
	* configure: Regenerate.