Revert "Trim some redundant Arm feature detection files"

[knightjoel]

This reverts commit d36bf85.

Issues:

Resolves AWS-LC-496

Description of changes:

d36bf85 was a merge from upstream. BoringSSL removed some 32-bit ARM stuff for OpenBSD, but the merge to aws-lc removed some aarch64 stuff, breaking the build on OpenBSD/arm64 platform (a regression from #962).

Testing:

I can successfully build aws-lc on OpenBSD/arm64 with this PR.

~/aws-lc-obsd-aarch64% cmake --build ./build
[...]
[588/595] Linking CXX executable ssl/test/bssl_shim
ld: warning: ssl_transfer.cc:30 (/home/jwk/aws-lc-obsd-aarch64/ssl/test/ssl_transfer.cc:30)(ssl/test/CMakeFiles/bssl_shim.dir/ssl_transfer.cc.o:(SSLTransfer::ResetSSL(TestConfig const*, std::__1::unique_ptr<ssl_st, bssl::internal::Deleter>*))): warning: rand() may return deterministic values, is that what you want?
[591/595] Linking CXX executable crypto/crypto_testld: warning: bio_md_test.cc:185 (/home/jwk/aws-lc-obsd-aarch64/crypto/pkcs7/bio/bio_md_test.cc:185)(crypto/CMakeFiles/crypto_test.dir/pkcs7/bio/bio_md_test.cc.o:(BIOMessageDigestTest_Randomized_Test::TestBody())): warning: rand() may return deterministic values, is that what you want?
[595/595] Linking CXX executable ssl/ssl_test

~/aws-lc-obsd-aarch64% uname -a
OpenBSD arm64 7.6 GENERIC.MP#196 arm64

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 78.87%. Comparing base (c9d48a6) to head (644f3fd).
Report is 16 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1979      +/-   ##
==========================================
+ Coverage   78.79%   78.87%   +0.08%     
==========================================
  Files         590      593       +3     
  Lines      101506   101927     +421     
  Branches    14401    14447      +46     
==========================================
+ Hits        79979    80400     +421     
+ Misses      20891    20882       -9     
- Partials      636      645       +9     

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