[PATCH] fix vm_events_fold_cpu() build breakage

fix vm_events_fold_cpu() build breakage

2.6.20-rc1 does not build properly if CONFIG_VM_EVENT_COUNTERS is set
and CONFIG_HOTPLUG is unset:

  CC      init/version.o
  LD      init/built-in.o
  LD      .tmp_vmlinux1
mm/built-in.o: In function `page_alloc_cpu_notify':
page_alloc.c:(.text+0x56eb): undefined reference to `vm_events_fold_cpu'
make: *** [.tmp_vmlinux1] Error 1

[akpm@osdl.org: cleanup]
Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/vmstat.h

@@ -74,7 +74,13 @@ static inline void count_vm_events(enum vm_event_item item, long delta)
 }
 
 extern void all_vm_events(unsigned long *);
+#ifdef CONFIG_HOTPLUG
 extern void vm_events_fold_cpu(int cpu);
+#else
+static inline void vm_events_fold_cpu(int cpu)
+{
+}
+#endif
 
 #else