* cp-tree.h (instantiate_decl): new boolean parameter,
	undefined_ok. Current behavior is equivalent to its being 0.
	* decl2.c (mark_used): Add new argument when calling instantiate_decl
	* pt.c (mark_decl_instantiated): Unconditionally make
	instantiations explicit unconditionally
	(do_decl_instantiation): Don't call SET_DECL_EXPLICIT_INSTANTIATION,
	since mark_decl_instantiated now does it.
	(instantiate_class_member): New.  Instantiate a member of an
	explicitly instantiated class template.
	(do_type_instantiation): Explicitly instantiate members of an
	explicitly instantiated class template.
	(instantiate_decl): if undefined_ok is nonzero, and if we're
	trying to explicitly instantiated a template with no definition,
	change it to an implicit instantiation.
	(instantiate_pending_templates): Add new argument to instantiate_decl.
	* tree.c (cp_cannot_inline_tree_fn): Likewise.

From-SVN: r82585