re PR debug/83941 (Debug info generated with -flto contains useless forwarders)

re PR debug/83941 (Debug info generated with -flto contains useless forwarders)

2018-09-25  Richard Biener  <rguenther@suse.de>

	PR debug/83941
	* dwarf2out.c (add_AT_external_die_ref): Remove now redundant
	GC-ification.
	(maybe_create_die_with_external_ref): Do not create
	DW_TAG_imported_unit here.
	(add_abstract_origin_attribute): Handle external BLOCK refs.
	(dwarf2out_abstract_function): Simplify LTO case.
	(dwarf2out_early_finish): Create DW_TAG_imported_unit explicitely
	rather than using maybe_create_die_with_external_ref.

From-SVN: r264573