AES-GCM enabled with AVX512 vAES and vPCLMULQDQ.

AES-GCM enabled with AVX512 vAES and vPCLMULQDQ.

Vectorized 'stitched' encrypt + ghash implementation of AES-GCM enabled
with AVX512 vAES and vPCLMULQDQ instructions (available starting Intel's
IceLake micro-architecture).

The performance details for representative IceLake Server and Client
platforms are shown below

Performance data:
OpenSSL Speed KBs/Sec
Intel(R) Xeon(R) Platinum 8380 CPU @ 2.30GHz (1Core/1Thread)
Payload in Bytes       16          64        256         1024        8192      16384
AES-128-GCM
  Baseline      478708.27   1118296.96  2428092.52  3518199.4   4172355.99  4235762.07
  Patched       534613.95   2009345.55  3775588.15  5059517.64  8476794.88  8941541.79
  Speedup            1.12         1.80        1.55        1.44        2.03        2.11

AES-256-GCM
  Baseline      399237.27   961699.9    2136377.65  2979889.15  3554823.37  3617757.5
  Patched       475948.13   1720128.51  3462407.12  4696832.2   7532013.16  7924953.91
  Speedup            1.19        1.79         1.62        1.58        2.12        2.19
Intel(R) Core(TM) i7-1065G7 CPU @ 1.30GHz (1Core/1Thread)
Payload in Bytes       16          64        256         1024        8192      16384
AES-128-GCM
  Baseline      259128.54   570756.43   1362554.16  1990654.57  2359128.88  2401671.58
  Patched       292139.47   1079320.95  2001974.63  2829007.46  4510318.59  4705314.41
  Speedup            1.13        1.89         1.47        1.42        1.91        1.96
AES-256-GCM
  Baseline      236000.34   550506.76   1234638.08  1716734.57  2011255.6   2028099.99
  Patched       247256.32   919731.34   1773270.43  2553239.55  3953115.14  4111227.29
  Speedup            1.05        1.67         1.44        1.49        1.97        2.03

Reviewed-by: TJ O'Dwyer, Marcel Cornu, Pablo de Lara
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17239)