re PR c/70093 (Instancing function with VM return type cases internal compiler error in 'assign_stack_temp_for_type'.)

	PR c/70093
	* c-typeck.c (build_function_call_vec): Create a TARGET_EXPR for
	nested functions returning VM types.

	* cgraphunit.c (cgraph_node::expand_thunk): Also build call to the
	function being thunked if the result type doesn't have fixed size.
	* gimplify.c (gimplify_modify_expr): Also set LHS if the result type
	doesn't have fixed size.

	* gcc.dg/nested-func-10.c: New test.
	* gcc.dg/nested-func-9.c: New test.

From-SVN: r234259