mm: only build per-node scan_unevictable functions when NUMA is enabled

Non-NUMA systems do never create these files anyway, since they are only
created by driver subsystem when NUMA is configured.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6cbc1aa..f5871ee 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2986,6 +2986,7 @@
 	return 0;
 }
 
+#ifdef CONFIG_NUMA
 /*
  * per node 'scan_unevictable_pages' attribute.  On demand re-scan of
  * a specified node's per zone unevictable lists for evictable pages.
@@ -3032,4 +3033,4 @@
 {
 	sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages);
 }
-
+#endif