Update version number to 2.1.9
diff --git a/ChangeLog b/ChangeLog
index 6bd210d..1d06476 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,6 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
-= mbed TLS 2.1.9 branch released xxxx-xx-xx
+= mbed TLS 2.1.9 branch released 2017-08-10
 
 Security
    * Fix authentication bypass in SSL/TLS: when authmode is set to optional,