c++: Originating and instantiating module

c++: Originating and instantiating module

With modules streamed entities have two new properties -- the module
that declares them and the module that instantiates them.  Here
'instantiate' applies to more than just templates -- for instance an
implicit member fn.  These may well be the same module.  This adds the
calls to places that need it.

	gcc/cp/
	* class.c (layout_class_type): Call set_instantiating_module.
	(build_self_reference): Likewise.
	* decl.c (grokfndecl): Call set_originating_module.
	(grokvardecl): Likewise.
	(grokdeclarator): Likewise.
	* pt.c (maybe_new_partial_specialization): Call
	set_instantiating_module, propagate DECL_MODULE_EXPORT_P.
	(lookup_template_class_1): Likewise.
	(tsubst_function_decl): Likewise.
	(tsubst_decl, instantiate_template_1): Likewise.
	(build_template_decl): Propagate module flags.
	(tsubst_template_dcl): Likewise.
	(finish_concept_definition): Call set_originating_module.
	* module.cc (set_instantiating_module, set_originating_module): Stubs.