Created a function for setting timeouts on keys

The keyctl_set_timeout function isn't exported to other parts of the
kernel, but I want to use it for the NFS idmapper.  I already have the
key, but I wanted a generic way to set the timeout.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/key.h b/include/linux/key.h
index 5253471..be3995d 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -276,6 +276,8 @@
 	return key ? key->serial : 0;
 }
 
+extern void key_set_timeout(struct key *, unsigned);
+
 /**
  * key_is_instantiated - Determine if a key has been positively instantiated
  * @key: The key to check.