openmp: Simplify fold_build_pointer_plus callers in omp-expand

openmp: Simplify fold_build_pointer_plus callers in omp-expand

Tobias mentioned in PR106449 that fold_build_pointer_plus already
fold_converts the second argument to sizetype if it doesn't already
have an integral type gimple compatible with sizetype.

So, this patch simplifies the callers of fold_build_pointer_plus in
omp-expand so that they don't do those conversions manually.

2022-07-29  Jakub Jelinek  <jakub@redhat.com>

	* omp-expand.cc (expand_omp_for_init_counts, expand_omp_for_init_vars,
	extract_omp_for_update_vars, expand_omp_for_ordered_loops,
	expand_omp_simd): Don't fold_convert second argument to
	fold_build_pointer_plus to sizetype.

(cherry picked from commit 4796d16de657d7c2720471e61432de0f4a5cb6df)