Simple build fix for x86_64 xenoprof makefile

Signed-Off-By: Magnus Damm <magnus@xxxxxxxxxxxxx>

--- 0047/arch/x86_64/oprofile/Makefile
+++ work/arch/x86_64/oprofile/Makefile	2006-04-07 15:01:13.000000000 +0900
@@ -11,7 +11,7 @@ DRIVER_OBJS = $(addprefix ../../../drive
 	oprofilefs.o oprofile_stats.o \
 	timer_int.o )
 
-ifdef
+ifdef CONFIG_X86_64_XEN
 OPROFILE-y := xenoprof.o
 else
 OPROFILE-y := init.o backtrace.o