[IA64] always build arch/ia64/lib/xor.o

Always build ia64 xor.o because multiple config options now depend on it.

Necessary to build .20-mm* on ia64 when, e.g., CONFIG_ASYNC_TX_DMA is
defined.  Don't know if '_ASYNC_TX_DMA makes sense on ia64.  If not, maybe
Kconfig should preclude it.

Could have defined a Kconfig option that defaults to true if MD_RAID456 ||
ASYNC_TX_DMA to control building of xor.o, but xor.o is only 848 bytes and
this IS ia64...

Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Bob Picco <bob.picco@hp.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/lib/Makefile

@@ -9,12 +9,11 @@ lib-y := __divsi3.o __udivsi3.o __modsi3.o __umodsi3.o			\
 	checksum.o clear_page.o csum_partial_copy.o			\
 	clear_user.o strncpy_from_user.o strlen_user.o strnlen_user.o	\
 	flush.o ip_fast_csum.o do_csum.o				\
-	memset.o strlen.o
+	memset.o strlen.o xor.o
 
 lib-$(CONFIG_ITANIUM)	+= copy_page.o copy_user.o memcpy.o
 lib-$(CONFIG_MCKINLEY)	+= copy_page_mck.o memcpy_mck.o
 lib-$(CONFIG_PERFMON)	+= carta_random.o
-lib-$(CONFIG_MD_RAID456)	+= xor.o
 
 AFLAGS___divdi3.o	=
 AFLAGS___udivdi3.o	= -DUNSIGNED