Compilation warning fixes on 32b platfrom with IAR

Fix compilation warnings with IAR toolchain, on 32 bit platform.
Reported by rahmanih in #683

This is based on work by Ron Eldor in PR #750, some of which was independently
fixed by Azim Khan and already merged in PR #1655.
diff --git a/ChangeLog b/ChangeLog
index 2d33641..233a05f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,8 @@
 Bugfix
    * Fix redundant declaration of mbedtls_ssl_list_ciphersuites. Raised by
      TrinityTonic. #1359.
+   * Fix compilation warnings with IAR toolchain, on 32 bit platform.
+     Reported by rahmanih in #683
 
 Changes
    * Support TLS testing in out-of-source builds using cmake. Fixes #1193.