make blk-core.c:request_cachep static again

request_cachep needlessly became global.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
index e9754dc..c013ca2 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -38,7 +38,7 @@
 /*
  * For the allocated request tables
  */
-struct kmem_cache *request_cachep;
+static struct kmem_cache *request_cachep;
 
 /*
  * For queue allocation