Refactor -frecord-gcc-switches.

Refactor -frecord-gcc-switches.

gcc/ChangeLog:

	* doc/tm.texi: Change argument of the record_gcc_switches
	hook and remove SWITCH_TYPE_* enum values.
	* dwarf2out.c (gen_producer_string): Move to opts.c and remove
	handling of the dwarf_record_gcc_switches option.
	(dwarf2out_early_finish): Use moved gen_producer_string
	function.
	* opts.c (gen_producer_string): New.
	* opts.h (gen_producer_string): New.
	* target.def: Change type of record_gcc_switches.
	* target.h (enum print_switch_type): Remove.
	(elf_record_gcc_switches): Change first argument.
	* toplev.c (MAX_LINE): Remove.
	(print_to_asm_out_file):  Likewise.
	(print_to_stderr): Likewise.
	(print_single_switch): Likewise.
	(print_switch_values): Likewise.
	(init_asm_output): Use new gen_producer_string function.
	(process_options): Likewise.
	* varasm.c (elf_record_gcc_switches): Just save the string argument
	to the ELF container.