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 (796202b) to head (d4bbbba).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1979      +/-   ##
==========================================
+ Coverage   78.86%   78.87%   +0.01%     
==========================================
  Files         593      593              
  Lines      101933   101933              
  Branches    14450    14451       +1     
==========================================
+ Hits        80386    80400      +14     
+ Misses      20903    20890      -13     
+ Partials      644      643       -1     

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[torben-hansen]

Looks like d36bf85 removed cpu_aarch64_openbsd.c that handles the 64-bit stuff. While it should have removed cpu_arm_openbsd.c that handles the 32-bit stuff, except this file doesn't exist in AWS-LC (a difference from BoringSSL).

Now see CryptoAlg-2781

[torben-hansen]

Actually, looks like there are some test setup to work through before PR is ready to merge.

But the revert part lgtm.