[PATCH v2 3/4] Output line numbers in CodeView section

[PATCH v2 3/4] Output line numbers in CodeView section

Outputs the DEBUG_S_LINES block in the CodeView .debug$S section, which
maps between line numbers and addresses.

You'll need a fairly recent version of GAS for the .secidx directive to
be recognized.

gcc/
	* dwarf2codeview.cc (DEBUG_S_LINES, LINE_LABEL): Define.
	(END_FUNC_LABEL): Likewise.
	(struct codeview_line, codeview_line_block): New structures.
	(codeview_function): Likewise.
	(line_label_num, func_label_num, funcs, last_func): New variables.
	(last_filename, last_file_id): Likewise.
	(codeview_source_line, write_line_numbers): New functions.
	(codeview_switch_text_section, codeview_end_epilogue): Likewise.
	(codeview_debug_finish): Call write_line_numbers.
	* dwarf2codeview.h (codeview_source_line): Prototype.
	(codeview_switch_text_secction, codeview_end_epilogue): Likewise.
	* dwarf2out.cc (dwarf2_end_epilogue): Add codeview support.
	(dwarf2out_switch_text_section): Likewise.
	(dwarf2out_source_line): Likewise.
	* opts.cc (finish_options): Handle codeview debugging symbols.