New aarch32-linux-nat.c

New aarch32-linux-nat.c

This patch is to move all the code about transferring
regcache <-> byte buffer for arm (aarch32) to a separate file
aarch32-linux-nat.c.  Then, in the following patch, aarch64 code
can use it to do multi-arch debugging.  This is a refactory patch.

gdb:

2015-07-07  Yao Qi  <yao.qi@linaro.org>

	* aarch32-linux-nat.c: New file.
	* aarch32-linux-nat.h: New file.
	* arm-linux-nat.c: Include aarch32-linux-nat.h.
	(fetch_regs): Move code to aarch32-linux-nat.c.  Call
	aarch32_gp_regcache_supply.
	(store_regs): Move code to aarch32-linux-nat.c.  Call
	aarch32_gp_regcache_collect.
	(fetch_vfp_regs): Move code to aarch32-linux-nat.c.  Call
	aarch32_vfp_regcache_supply.
	(store_vfp_regs): Move code to aarch32-linux-nat.c.  Call
	aarch32_vfp_regcache_collect.
	* config/arm/linux.mh (NATDEPFILES): Add aarch32-linux-nat.o.