c-family: Add some more ARRAY_SIZE uses

These two spots were just non-standard, because they divided
sizeof (omp_pragmas_simd) by sizeof (*omp_pragmas) and not
the expected sizeof (*omp_pragmas_simd) and so weren't converted
into ARRAY_SIZE.  Both of the latter sizes are the same though,
as both arrays have the same type, so this patch doesn't change
anything but readability.

2024-08-09  Jakub Jelinek  <jakub@redhat.com>

	* c-pragma.cc (c_pp_lookup_pragma): Use ARRAY_SIZE in
	n_omp_pragmas_simd initializer.
	(init_pragmas): Likewise.