Capture adjustments for P0588R1.

Capture adjustments for P0588R1.

	* semantics.c (process_outer_var_ref): Capture variables when
	they are named; complain about non-capture uses when odr-used.
	* expr.c (mark_use): Rvalue use looks through capture proxy.
	* constexpr.c (potential_constant_expression_1): Improve error about
	use of captured variable.
	* lambda.c (need_generic_capture, dependent_capture_r)
	(do_dependent_capture, processing_nonlambda_template): Remove.
	* call.c (build_this): Remove uses of the above.
	* decl.c (cp_finish_decl): Likewise.
	* semantics.c (maybe_cleanup_point_expr)
	(maybe_cleanup_point_expr_void, finish_goto_stmt)
	(maybe_convert_cond): Likewise.
	* typeck.c (check_return_expr): Likewise.

From-SVN: r254713