* xcoff.c: Initial support for DWARF debug sections in XCOFF.
	(STYP_DWARF, SSUBTYP_DW*): Define.
	(enum dwarf_section): Define.
	(struct dwsect_info): Define.
	(xcoff_add): Look for DWARF sections, pass them to
	backtrace_dwarf_add.

From-SVN: r253297