mm: use IS_ENABLED(CONFIG_NUMA) instead of NUMA_BUILD

We don't need custom NUMA_BUILD anymore, since we have handy
IS_ENABLED().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index d0a7967..31e8041 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -266,7 +266,7 @@
 
 static inline int gfp_zonelist(gfp_t flags)
 {
-	if (NUMA_BUILD && unlikely(flags & __GFP_THISNODE))
+	if (IS_ENABLED(CONFIG_NUMA) && unlikely(flags & __GFP_THISNODE))
 		return 1;
 
 	return 0;