Detect all Apple M* CPUs and enable the wide multiplier assembly implementations

[andrewhop]

Description of changes:

Looking at the benchmarks on https://github.com/ctz/graviola/ I noticed AWS-LC was slower than expected. Those benchmarks were performed on an M2 Mac and previously AWS-LC was only checking for M1 CPUs. This change opts all Apple M* CPUs in the alt/wide multiplier implementations. A future Apple M CPU might benefit from the non-alt implementation, but for now it seems like all M CPUs benefit from the alt implementation and this is a sane default.

Call-outs:

I think this is safe because both implementations use the same instructions, it's just a reordering. So if a future M CPU doesn't support the wide multiplier it will still work it will just be slower than if it was using the non-alt implementation.

Testing:

Tested on an M1 and M3 that the alt implementation is picked and is faster. M3 before:

Did 29631 EVP ECDH P-224 operations in 1018316us (29098.0 ops/sec)
Did 30000 EVP ECDH P-256 operations in 1020237us (29404.9 ops/sec)
Did 5840 EVP ECDH P-384 operations in 1000133us (5839.2 ops/sec)
Did 3630 EVP ECDH P-521 operations in 1096572us (3310.3 ops/sec)
Did 5430 EVP ECDH secp256k1 operations in 1000506us (5427.3 ops/sec)
Did 41000 EVP ECDH X25519 operations in 1009621us (40609.3 ops/sec)

M3 After

Did 30233 EVP ECDH P-224 operations in 1013635us (29826.3 ops/sec)
Did 31000 EVP ECDH P-256 operations in 1022186us (30327.2 ops/sec)
Did 7227 EVP ECDH P-384 operations in 1076336us (6714.4 ops/sec)
Did 4690 EVP ECDH P-521 operations in 1042402us (4499.2 ops/sec)
Did 5710 EVP ECDH secp256k1 operations in 1051837us (5428.6 ops/sec)
Did 52000 EVP ECDH X25519 operations in 1008149us (51579.7 ops/sec)

As expected P-224 and P-256 are unaffected, while 384/521/X25519 which do use s2n-bignum are much faster.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.48%. Comparing base (ad93747) to head (17028e8).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1901      +/-   ##
==========================================
+ Coverage   78.45%   78.48%   +0.02%     
==========================================
  Files         585      585              
  Lines       99516    99517       +1     
  Branches    14244    14243       -1     
==========================================
+ Hits        78080    78105      +25     
+ Misses      20796    20777      -19     
+ Partials      640      635       -5     

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[ctz]

Nice! I had assumed this was coming from shipping the fastest implementation on Graviton; I didn't realise you were switching between them at runtime :)