Fix various latent issues revealed by P0732 work.

Fix various latent issues revealed by P0732 work.

The initialized_type hunk fixes handling of void AGGR_INIT_EXPRs that call a
non-constructor; an AGGR_INIT_EXPR can have void type if its initialization
semantics are more complicated than just expanding the call.

The cxx_eval_vec_init_1 hunk corrects AGGR_INIT_EXPRs that were
nonsensically built to initialize an object of void type.  And the
build_aggr_init_expr hunk makes sure we don't do that again.

The ocp_convert and cxx_eval_outermost_constant_expr hunks deal with making
sure that a constant CONSTRUCTOR has the right type.

	* cvt.c (ocp_convert): Don't wrap a CONSTRUCTOR in a NOP_EXPR.
	* constexpr.c (initialized_type): Fix AGGR_INIT_EXPR handling.
	(cxx_eval_vec_init_1): Correct type of AGGR_INIT_EXPR.
	(cxx_eval_outermost_constant_expr): Make sure a CONSTRUCTOR has the
	right type.  Don't wrap a CONSTRUCTOR if one was passed in.
	* tree.c (build_aggr_init_expr): Check for void.

From-SVN: r265788