gmtime: Remove special treatment for IAR
Previous commits attempted to use `gmtime_s()` for IAR systems; however,
this attempt depends on the use of C11 extensions which lead to incompatibility
with other pieces of the library, such as the use of `memset()` which is
being deprecated in favor of `memset_s()` in C11.
diff --git a/ChangeLog b/ChangeLog
index 1ba5f0e..0a60f70 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,8 +7,8 @@
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 automatically select implementations for Windows, POSIX
- C libraries and IAR.
+ is only able to automatically select implementations for Windows and POSIX
+ C libraries.
Bugfix
* Fixes an issue with MBEDTLS_CHACHAPOLY_C which would not compile if