* dwarf2read.c (struct dwo_file): Add/tweak comments.
	(lookup_dwo_unit_in_dwp): Renamed from lookup_dwo_in_dwp.  Remove
	arg "htab".  All callers updated.
	(create_debug_types_hash_table): Remove redundant copy of
	abbrev_section.
	(create_dwo_in_dwp): Tweak comments.
	(read_str_index): Tweak comment.  Record dwarf form name in static
	local.