Add ChangeLog entry for Windows threading fix
diff --git a/ChangeLog b/ChangeLog
index 8c82d08..09afc1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,9 @@
* Close a test gap in (D)TLS between the client side and the server side:
test the handling of large packets and small packets on the client side
in the same way as on the server side.
+ * Change the use of Windows threading to use Microsoft Visual C++ runtime
+ calls, rather than Win32 API calls directly. This is necessary to avoid
+ conflict with C runtime usage. Found and fixed by irwir.
= mbed TLS 2.1.15 branch released 2018-08-31