Enable Keccak AVX-512 support

After testing, I think that OpenSSL 3.0.8 (and older) as available in current
Fedora 38, Keccak acceleration with AVX-512 is seemingly not activated. I
performed a timing with a file that I generated as follows:

dd if=/dev/zero of=/dev/shm/file count=8 bs=1GB

I am maintaining my own crypto library [1]. That library contains an AVX-512
implementation whose timing is:

$ time build/hash/tests/hasher -h SHA3-512 -f /dev/shm/file
Message digest =
b2cc3439955e990d319bfc5b0bc1401ae18de07ff275abad5fec77e0f921e8e3d77b9a58b769cd44c7b0fa5c300782a97d151259bd63a76cd16f278c3a4c0126

real 0m54,888s
user 0m53,969s
sys 0m0,762s

Using OpenSSL's implementation on the very same system:

time openssl dgst -sha3-512 /dev/shm/file
SHA3-512(/dev/shm/file)=
b2cc3439955e990d319bfc5b0bc1401ae18de07ff275abad5fec77e0f921e8e3d77b9a58b769cd44c7b0fa5c300782a97d151259bd63a76cd16f278c3a4c0126

real 1m20,355s
user 1m18,127s
sys 0m1,984s

After forcing my implementation to use AVX2 (as opposed to AVX-512):

$ time build/hash/tests/hasher -h SHA3-512 -f /dev/shm/file
Message digest =
b2cc3439955e990d319bfc5b0bc1401ae18de07ff275abad5fec77e0f921e8e3d77b9a58b769cd44c7b0fa5c300782a97d151259bd63a76cd16f278c3a4c0126

real 1m17,026s
user 1m15,906s
sys 0m0,901s

You see, it seems to be the case that AVX-512 support is not active for Keccak.

[1] https://www.chronox.de/leancrypto.html

Start by reproducing the reported openssl dgst -sha3-512 /dev/shm/file timing and compare it with the AVX-2 and AVX-512 timings described in the issue. Trace the Keccak/SHA3 implementation and CPU-feature dispatch to determine whether AVX-512 is selected; done means AVX-512 acceleration is active where supported and the reported digest remains unchanged.