Remove VEC_RSHIFT_EXPR tree code, now unused

Remove VEC_RSHIFT_EXPR tree code, now unused

	* fold-const.c (const_binop): Remove code handling VEC_RSHIFT_EXPR.
	* tree-cfg.c (verify_gimple_assign_binary): Likewise.
	* tree-inline.c (estimate_operator_cost): Likewise.
	* tree-pretty-print.c (dump_generic_node, op_code_prio, op_symbol_code):
	Likewise.

	* tree-vect-generic.c (expand_vector_operations_1): Remove assertion
	against VEC_RSHIFT_EXPR.

	* optabs.h (expand_vec_shift_expr): Remove.
	* optabs.c (optab_for_tree_code): Remove case VEC_RSHIFT_EXPR.
	(expand_vec_shift_expr): Remove.
	* tree.def (VEC_RSHIFT_EXPR): Remove

From-SVN: r217510