[gtk+] Add a release note about X without render

[Matthias Clasen <matthiasc src gnome org>]

commit 1feeb6bb4dd1a9d319074b90213bc9d6fe9b71ad
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Aug 28 23:01:18 2014 -0400

    Add a release note about X without render
    
    This reflects the findings in
    https://bugzilla.gnome.org/show_bug.cgi?id=735294

 README.in |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/README.in b/README.in
index badea8c..9500024 100644
--- a/README.in
+++ b/README.in
@@ -95,6 +95,10 @@ Release notes for 3.14
   for event handling. Traditional event handlers in derived widgets are still
   being called.
 
+* Using GTK+ under X11 without the X Render extension has been observed
+  to be problematic. This combination is using code paths in cairo and
+  graphics drivers which are rarely tested and likely buggy.
+
 Release notes for 3.12
 ======================