* gdb.dwarf2/dw2-abs-hi-pc.exp: Build tests with "nodebug".
	* dwarf2read.c (struct dwarf2_cu): Improve comments for members
	addr_base, ranges_base.
	* dwarf2read.c (init_cutu_and_read_dies_no_follow): Fix comments.
	Remove argument abbrev_section.  All callers updated.
	* dwarf2read.c (read_str_index): Delete arg cu.  All callers updated.