Move target-dcache out of target.c

Move target-dcache out of target.c

This patch moves target_dcache related code out of target.c.

gdb:

2013-11-20  Yao Qi  <yao@codesourcery.com>

	* Makefile.in (SFILES):Add target-dcache.c.
	(HFILES_NO_SRCDIR): Add target-dcache.h.
	(COMMON_OBS): Add target-dcache.o.
	* dcache.c: Remove inclusion to "target.h".  Include
	"target-dcache.h".
	* memattr.c: Include "target-dcache.h".
	* top.c: Likewise.
	* tracepoint.c: Likewise.
	* target.c: (stack_cache_enabled_p_1): Move to
	target-dcache.c.
	(stack_cache_enabled_p): Likewise.
	(set_stack_cache_enabled_p): Likewise.
	(show_stack_cache_enabled_p): Likewise.
	(target_dcache, target_dcache_init_p): Likewise.
	(target_dcache_invalidate): Likewise.
	(target_dcache_get, target_dcache_get_or_init): Likewise.
	(memory_xfer_partial_1): Call function stack_cache_enabled.
	(initialize_target): Move code to target-dcache.c.
	* target.h (target_dcache_invalidate): Move to
	target-dcache.h.
	(target_dcache_get): Likewise.
	* target-dcache.c: New.
	* target-dcache.h: New.