Log Message:
libgcrypt: updated to 1.9.3

Noteworthy changes in version 1.9.3 (2021-04-19)
------------------------------------------------

 * Bug fixes:
   - Fix build problems on i386 using gcc-4.7.
   - Fix checksum calculation in OCB decryption for AES on s390.
   - Fix a regression in gcry_mpi_ec_add related to certain usages of
     curve 25519.
   - Fix a symbol not found problem on Apple M1.
   - Fix for Apple iOS getentropy peculiarity.
   - Make keygrip computation work for compressed points.

* Performance:
   - Add x86_64 VAES/AVX2 accelerated implementation of Camellia.
   - Add x86_64 VAES/AVX2 accelerated implementation of AES.
   - Add VPMSUMD acceleration for GCM mode on PPC.

 * Internal changes.
   - Harden MPI conditional code against EM leakage.
   - Harden Elgamal by introducing exponent blinding.
   - Fix memory leaks in the error code paths of EdDSA.