* dwarf2.h (DW_AT_GNU_macros): New.
	(enum dwarf_macro_record_type): New enum.  Add DW_MACRO_GNU_*.

	* dwarf2out.c (struct macinfo_struct): Change code to unsigned char.
	(DEBUG_MACRO_SECTION, DEBUG_MACRO_SECTION_LABEL): Define.
	(dwarf_attr_name): Handle DW_AT_GNU_macros.
	(dwarf2out_define): If the vector is empty and
	lineno is 0, emit a dummy entry first.
	(dwarf2out_undef): Likewise.  Remove redundant semicolon.
	(htab_macinfo_hash, htab_macinfo_eq, output_macinfo_op,
	optimize_macinfo_range): New functions.
	(output_macinfo): Use them.  If !dwarf_strict and .debug_str is
	mergeable, optimize longer strings using
	DW_MACRO_GNU_{define,undef}_indirect and if HAVE_COMDAT_GROUP,
	optimize longer sequences of define/undef ops from headers
	using DW_MACRO_GNU_transparent_include.  For !dwarf_strict
	emit a section headers.
	(dwarf2out_init): For !dwarf_strict set debug_macinfo_section
	and macinfo_section_label to DEBUG_MACRO_SECTION
	resp. DEBUG_MACRO_SECTION_LABEL.
	(dwarf2out_finish): For !dwarf_strict emit DW_AT_GNU_macros
	instead of DW_AT_macro_info.

From-SVN: r176653