re PR lto/53808 (Undefined symbol when building a library with lto)

re PR lto/53808 (Undefined symbol when building a library with lto)

	PR lto/53808
	PR c++/61659
	* pt.c (push_template_decl_real): Set DECL_COMDAT on templates.
	(check_explicit_specialization): Clear it on specializations.
	* decl.c (duplicate_decls, start_decl): Likewise.
	(grokmethod, grokfndecl): Set DECL_COMDAT on inlines.
	* method.c (implicitly_declare_fn): Set DECL_COMDAT.  Determine
	linkage after setting the appropriate flags.
	* tree.c (decl_linkage): Don't check DECL_COMDAT.
	* decl2.c (mark_needed): Mark clones.
	(import_export_decl): Not here.

From-SVN: r213307