Don't output CodeView line numbers for inlined functions

Don't output CodeView line numbers for inlined functions

If we encounter an inlined function, treat it as another
codeview_function, and skip over these when outputting line numbers.
This information will instead be output as part of the S_INLINESITE
symbols.

gcc/
	* dwarf2codeview.cc (struct codeview_function): Add parent and
	inline_block fields.
	(cur_func): New global variable.
	(new_codeview_function): New function.
	(codeview_source_line): Call new_codeview_function, and use cur_func
	instead of last_func.
	(codeview_begin_block): New function.
	(codeview_end_block): New function.
	(write_line_numbers): No longer free data as we go along.
	(codeview_switch_text_section): Call new_codeview_function, and use
	cur_func instead of last_func.
	(codeview_end_epilogue): Use cur_func instead of last_func.
	(codeview_debug_finish): Free funcs list and its contents.
	* dwarf2codeview.h (codeview_begin_block): Add declaration.
	(codeview_end_block): Add declaration.
	* dwarf2out.cc (dwarf2out_begin_block): Call codeview_begin_block if
	outputting CodeView debug info.
	(dwarf2out_end_block): Call codeview_end_block if outputting CodeView
	debug info.