fix PVS studio reported bugs

2020-04-17  Richard Biener  <rguenther@suse.de>

	PR other/94629
	* cgraphclones.c (cgraph_node::create_clone): Remove duplicate
	initialization.
	* dwarf2out.c (dw_val_equal_p): Fix pasto in
	dw_val_class_vms_delta comparison.
	* optabs.c (expand_binop_directly): Fix pasto in commutation
	check.
	* tree-ssa-sccvn.c (vn_reference_lookup_pieces): Fix pasto in
	initialization.