MBEDTLS_NO_INT64_DIVISION -> MBEDTLS_NO_UDBL_DIVISION

Changed the option to disable the use of 64-bit division, to an option
to disable the use of double-width division, whether that's 64 or 128-bit.
diff --git a/ChangeLog b/ChangeLog
index 6c2f783..c3ec3c3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -16,6 +16,13 @@
      qualifier from the functions mbedtls_aes_decrypt, mbedtls_aes_encrypt,
      mbedtls_ssl_ciphersuite_uses_ec and mbedtls_ssl_ciphersuite_uses_psk.
 
+Changes
+   * Added config.h option MBEDTLS_NO_UDBL_DIVISION, to prevent the use of
+     64-bit division.
+   * Added config.h option MBEDTLS_TYPE_UDBL to allow configuring the
+     double-width integer type used in the bignum module when the compiler is
+     unknown.
+
 Bugfix
    * Add a check if iv_len is zero, and return an error if it is zero. reported
      by roberto. #716