* common.opt (flag_debug_types_section): Default to 0.
	(dwarf_version): Default to 4.
	(dwarf_record_gcc_switches): Default to 1.
	(dwarf_strict): Default to 0.
	* toplev.c (process_options): Don't handle dwarf_strict
	or dwarf_version here.
	* config/vxworks.c (vxworks_override_options): Don't
	test whether dwarf_strict or dwarf_version are negative,
	instead test !global_options_set.x_dwarf_*.
	* config/darwin.c (darwin_override_options): Default to
	dwarf_version 2.
	* doc/invoke.texi: Note that -gdwarf-4, -grecord-gcc-switches
	and -fno-debug-types-section are now the default.

From-SVN: r186835