Require lvalues as specified by the standard.

	* typeck.c (lvalue_or_else): Use real_lvalue_p.
	(cp_build_addr_expr_1): Split out of cp_build_unary_op.
	(cp_build_addr_expr, cp_build_addr_expr_strict): Interfaces.
	(decay_conversion, get_member_function_from_ptrfunc): Adjust.
	(build_x_unary_op, build_reinterpret_cast_1): Adjust.
	(build_const_cast_1): Adjust.
	* cp-tree.h: Declare new fns.
	* call.c (build_this, convert_like_real, build_over_call): Adjust.
	(initialize_reference): Adjust.
	* class.c (build_base_path, convert_to_base_statically): Adjust.
	(build_vfn_ref, resolve_address_of_overloaded_function): Adjust.
	* cvt.c (build_up_reference, convert_to_reference): Adjust.
	* decl.c (register_dtor_fn): Adjust.
	* decl2.c (build_offset_ref_call_from_tree): Adjust.
	* except.c (initialize_handler_parm): Adjust.
	* init.c (build_offset_ref, build_delete, build_vec_delete): Adjust.
	* rtti.c (build_dynamic_cast_1, tinfo_base_init): Adjust.
	* tree.c (stabilize_expr): Adjust.

From-SVN: r164666