Fix ENOMEM error sign.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-By: Alasdair G Kergon <agk@redhat.com>

--- linux-2.6.17.orig/drivers/md/dm-snap.c	2006-09-13 16:32:15.000000000 +0100
+++ linux-2.6.17/drivers/md/dm-snap.c	2006-09-13 16:32:51.000000000 +0100
@@ -1036,7 +1036,7 @@ static int __origin_write(struct list_he
 
 		pe = __find_pending_exception(snap, bio);
 		if (!pe) {
-			__invalidate_snapshot(snap, pe, ENOMEM);
+			__invalidate_snapshot(snap, pe, -ENOMEM);
 			goto next_snapshot;
 		}