nfsd4: fix missing "static"

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 4767429..2b8e9a9 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -1029,7 +1029,7 @@
 	return ret;
 }
 
-struct notifier_block nfsd4_cld_block = {
+static struct notifier_block nfsd4_cld_block = {
 	.notifier_call = rpc_pipefs_event,
 };