Added ChangeLog entry for 64-bit ILP32 fix

Fixes #849
diff --git a/ChangeLog b/ChangeLog
index 8447365..c9b416d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -269,6 +269,7 @@
      Vranken.
    * Fix a numerical underflow leading to stack overflow in mpi_read_file()
      that was triggered uppon reading an empty line. Found by Guido Vranken.
+   * Fix test_suite_pk to work on 64-bit ILP32 systems. #849
 
 Changes
    * Send fatal alerts in more cases. The previous behaviour was to skip