tree-optimization/113898 - ICE with sanity checking for VN ref adjustment

The following fixes a missing add to the accumulated offset when
adjusting an ARRAY_REF op for value-ranges applied to by
get_ref_base_and_extent.

	PR tree-optimization/113898
	* tree-ssa-sccvn.cc (copy_reference_ops_from_ref): Add
	missing accumulated off adjustment.

	* gcc.dg/torture/pr113898.c: New testcase.