Remove a.out NetBSD and OpenBSD hosts

Remove a.out NetBSD and OpenBSD hosts

gdb/
2013-09-21  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Remove a.out NetBSD and OpenBSD hosts.
	* NEWS (Removed native configurations): New.
	* config/arm/nbsdaout.mh: Remove.
	* config/i386/nbsdaout.mh: Remove.
	* config/i386/obsdaout.mh: Remove.
	* config/m68k/nbsdaout.mh: Remove.
	* config/sparc/nbsdaout.mh: Remove.
	* config/vax/nbsdaout.mh: Remove.
	* configure.host (arm*-*-netbsd*, i[34567]86-*-netbsd*)
	(i[34567]86-*-openbsd[0-2].*, i[34567]86-*-openbsd3.[0-3])
	(m68*-*-netbsd*, sparc-*-netbsd*, vax-*-netbsd*): Add them to obsolete
	error.
	(arm*-*-netbsd*, i[34567]86-*-netbsd*, i[34567]86-*-openbsd[0-2].*)
	(i[34567]86-*-openbsd3.[0-3], m68*-*-netbsd*, sparc-*-netbsdaout*)
	(sparc-*-netbsd*, vax-*-netbsd*): Remove.