Fix bug 6859 (GTK signal macros don't work in non-GCC compilers
	for void return types).

	* libnautilus-extensions/nautilus-gtk-macros.h:
	Replaced old macros that accidentally relied on gccisms with
	new ones that are portable to other compilers.

		NAUTILUS_CALL_PARENT_CLASS is replaced by
			NAUTILUS_CALL_PARENT
		    and NAUTILUS_CALL_PARENT_WITH_RETURN_VALUE.

		NAUTILUS_CALL_VIRTUAL is replaced by
			NAUTILUS_CALL_METHOD
		    and NAUTILUS_CALL_METHOD_WITH_RETURN_VALUE

	* components/adapter/nautilus-adapter-control-embed-strategy.c:
	(nautilus_adapter_control_embed_strategy_destroy):
	* components/adapter/nautilus-adapter-embed-strategy.c:
	(nautilus_adapter_embed_strategy_destroy),
	(nautilus_adapter_embed_strategy_get_widget),
	(nautilus_adapter_embed_strategy_get_zoomable):
	* components/adapter/nautilus-adapter-embeddable-embed-strategy.c:
	(nautilus_adapter_embeddable_embed_strategy_destroy):
	* components/adapter/nautilus-adapter-factory-serv...