Add FreeBSD/arm architecture.

Add FreeBSD/arm architecture.

Support for collecting and supplying general purpose and floating
point registers is provided along with signal frame unwinding.  While
FreeBSD/arm kernels do populate NT_FPREGSET notes, they are always
zero-filled, so this implementation ignores them.  Recent FreeBSD/arm
kernels generate NT_ARM_VFP notes which are used to supply
floating-point registers.  As with Linux, the AT_HWCAP feature flags
are used to determine the correct target description.

gdb/ChangeLog:

	* Makefile.in (ALL_TARGET_OBS): Add arm-fbsd-tdep.o.
	(ALLDEPFILES): Add arm-fbsd-tdep.c.
	* NEWS: Mention new FreeBSD/arm target.
	* configure.tgt: Add arm*-*-freebsd*.
	* arm-fbsd-tdep.c: New file.
	* arm-fbsd-tdep.h: New file.