Fix potential heap corruption on Windows

If len is large enough, when cast to an int it will be negative and then the
test if( len > MAX_PATH - 3 ) will not behave as expected.
diff --git a/ChangeLog b/ChangeLog
index ac33f5b..85909ca 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,9 @@
    * Fix potential double free if mbedtls_ssl_conf_psk() is called more than
      once and some allocation fails. Cannot be forced remotely. Found by Guido
      Vranken, Intelworks.
+   * Fix potential heap corruption on Windows when
+     mbedtls_x509_crt_parse_path() is passed a path longer than 2GB. Cannot be
+     triggered remotely. Found by Guido Vranken, Interlworks.
    * The X509 max_pathlen constraint was not enforced on intermediate
      certificates. Found by Nicholas Wilson, fix and tests provided by
      Janos Follath. #280 and #319