[CMAKE] Enable SSE4.1, SHA-NI and AVX2 for the crypto library
[CMAKE] Enable SSE4.1, SHA-NI and AVX2 for the crypto library

Summary: They are enabled if the hardware support the appropriated instructions.

Test Plan:
Edit `src/bench/bench_bitcoin.cpp` and replace the line:
  SHA256AutoDetect();
With:
  std::cout << SHA256AutoDetect() <<std::endl;
Then
  cmake -GNinja ..
  ninja bitcoin-bench
  ./src/bench/bitcoin-bench -filter=SHA256
Check that the enabled features match your hardware capabilities by
looking at the CPU flags in `/proc/cpuinfo`.
Checked with all flags and without avx2.

Run the gitian builds.

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D4706

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