Add ChangeLog entry for configurable gmtime() in platform
diff --git a/ChangeLog b/ChangeLog
index d8b2829..5aa54e5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,14 @@
= mbed TLS x.x.x branch released xxxx-xx-xx
+API Changes
+ * Extend the platform module with an abstraction mbedtls_platform_gmtime()
+ whose implementation should behave as a thread safe version of gmtime().
+ This allows users to configure such an implementation at compile time when
+ the target system cannot be deduced automatically. At this stage Mbed TLS
+ is only able to configure implementations for Windows and POSIX C
+ libraries.
+
Bugfix
* Fixes an issue with MBEDTLS_CHACHAPOLY_C which would not compile if
MBEDTLS_ARC4_C and MBEDTLS_CIPHER_NULL_CIPHER weren't also defined. #1890
