Log Message:
Updated libgcrypt to 1.7.4.

Noteworthy changes in version 1.7.4 (2016-12-09)  [C21/A1/R4]
------------------------------------------------

 * Performance:

   - More ARMv8/AArch32 improvements for AES, GCM, SHA-256, and SHA-1.

   - Add ARMv8/AArch32 assembly implementation for Twofish and
     Camellia.

   - Add bulk processing implementation for ARMv8/AArch32.

   - Add Stribog OIDs.

   - Improve the DRBG performance and sync the code with the Linux
     version.

 * Internal changes:

   - When secure memory is requested by the MPI functions or by
     gcry_xmalloc_secure, they do not anymore lead to a fatal error if
     the secure memory pool is used up.  Instead new pools are
     allocated as needed.  These new pools are not protected against
     being swapped out (mlock can't be used).  However, these days
     this is considered a minor issue and can easily be mitigated by
     using encrypted swap space.

 * Bug fixes:

   - Fix GOST 28147 CryptoPro-B S-box.

   - Fix error code handling of mlock calls.