[libgee] Fix warnings

[Maciej Marcin Piechotka <mpiechotka src gnome org>]

commit 967b09b1952cf1ce6a3952b266e7ac76940c2663
Author: Maciej Piechotka <uzytkownik2 gmail com>
Date:   Thu Jan 5 15:07:10 2012 +0100

    Fix warnings

 gee/concurrentlist.vala |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gee/concurrentlist.vala b/gee/concurrentlist.vala
index 356157d..e33deb1 100644
--- a/gee/concurrentlist.vala
+++ b/gee/concurrentlist.vala
@@ -53,7 +53,7 @@ public class Gee.ConcurrentList<G> : AbstractList<G> {
 	~ConcurrentList () {
 		HazardPointer.Context ctx = new HazardPointer.Context ();
 		_head = null;
-		HazardPointer.set_pointer<Node<G>> (&_tail, null);
+		HazardPointer.set_pointer<Node<G>?> (&_tail, null);
 	}
 
 	/**
@@ -398,8 +398,8 @@ public class Gee.ConcurrentList<G> : AbstractList<G> {
 		}
 
 		inline ~Node () {
-			HazardPointer.set_pointer<Node<G>> (&_succ, null, 3);
-			HazardPointer.set_pointer<Node<G>> (&_backlink, null);
+			HazardPointer.set_pointer<Node<G>?> (&_succ, null, 3);
+			HazardPointer.set_pointer<Node<G>?> (&_backlink, null);
 #if DEBUG
 			G? old_data = HazardPointer.exchange_pointer (&_data, null);
 			stderr.printf ("  Freeing node %p (with data %p)\n", this, old_data);
@@ -573,7 +573,7 @@ public class Gee.ConcurrentList<G> : AbstractList<G> {
 #if DEBUG
 			stderr.printf ("      Setting backlink from %p to %p\n", this, backlink);
 #endif
-			HazardPointer.compare_and_exchange_pointer<Node<G>> (&_backlink, null, backlink);
+			HazardPointer.compare_and_exchange_pointer<Node<G>?> (&_backlink, null, backlink);
 		}
 
 		public Node<G> *_succ;