re PR middle-end/45307 (Stores expanding to no RTL not removed by tree optimizers...

re PR middle-end/45307 (Stores expanding to no RTL not removed by tree optimizers, Empty ctors/dtors not eliminated)

	PR c++/45307
	PR c++/17736
	* cgraph.h (cgraph_only_called_directly_p,
	cgraph_can_remove_if_no_direct_calls_and_refs_p): Handle
	static cdtors.
	* cgraphunit.c (cgraph_decide_is_function_needed): Static cdtors
	are not needed.
	(cgraph_finalize_function): Static cdtors are reachable.
	(cgraph_mark_functions_to_output): Use cgraph_only_called_directly_p.

	* gcc.dg/ipa/ctor-empty-1.c: Add testcase.
	* g++.dg/tree-ssa/empty-2.C: Check that constructor got optimized out.

From-SVN: r163439