Add Changelog entry for #482

Add Changelog entry for inline assembly/literal strings too long issue with
Clang.
diff --git a/ChangeLog b/ChangeLog
index 513f24f..13604e8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,9 @@
      invalidated keys of a lifetime of less than a 1s. Fixes #1968.
    * Fix failure in hmac_drbg in the benchmark sample application, when
      MBEDTLS_THREADING_C is defined. Found by TrinityTonic, #1095
+   * Fix for Clang, which was reporting a warning for the bignum.c inline
+     assembly for AMD64 targets creating string literals greater than those
+     permitted by the ISO C99 standard. Found by Aaron Jones. Fixes #482.
 
 Changes
    * Add tests for session resumption in DTLS.