tree-optimization/127000 - revise (T *)(ptr - ptr_cst) pattern

The following revises the earlier fix which was avoiding
build_fold_addr_expr_with_type.  Instead the following applies
the GENERIC simplification that this function should have done
to the pattern directly, canonicalizing (T *)(ptr - ptr_cst)
to (T *)ptr p+ cst.  The pattern was originally added with
r10-7127-gcb99630f254aae.

	PR tree-optimization/127000
	* match.pd ((T *)(ptr - ptr_cst)): Canonicalize directly
	to (T *)ptr p+ cst.