[glib] Add a note about atomic changes

[Matthias Clasen <matthiasc src gnome org>]

commit 151016922d59facc158fddb51a6ed444fe65569c
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue May 31 14:53:30 2011 -0400

    Add a note about atomic changes

 NEWS |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/NEWS b/NEWS
index 6ea10ce..e884c0e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,15 @@
+Overview of changes from GLib 2.29.4 to 2.29.6
+==============================================
+
+* Atomic operations have been rewritten from scratch
+  to take care of gcc builtins where possible.
+  As a side-effect of this, calls to g_atomic_ API with explicit
+  casts may now be problematic; if that happens to you, try first
+  to remove the casts.
+  Another side-effect of the rewrite is that g_atomic_int_exchange_and_add
+  has been deprecated in favor of g_atomic_int_add.
+
+
 Overview of changes from GLib 2.29.2 to 2.29.4
 ==============================================