ppc64le: support OPENSSL_ppccap ENV variable

[justsmth]

Issues:

CryptoAlg-2425

Description of changes:

• Architectures for which we have custom assembly implementations need to provide a mechanism for the environment to alter the CPU capabilities that are detected at runtime.
• This PR adds support for setting a OPENSSL_ppccap environment variable for this purpose.

Testing:

• Without setting the environment variable: 55ms

[ RUN      ] AESTest.TestVectors
[       OK ] AESTest.TestVectors (55 ms)

• After setting export OPENSSL_ppccap=0x0000000000000000: 216ms

[ RUN      ] AESTest.TestVectors
[       OK ] AESTest.TestVectors (216 ms)

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.

[jvdsn]

I can't really test it because I don't have a ppc platform, but the code looks like what I expected.

[skmcgrail]

Does this need any any special handling in the delocater? I believe OPENSSL_armcap_P and OPENSSL_ia32cap_P both have special delocate logic handling. Not sure if FIPS is in play for this architecture in question.

[justsmth]

Does this need any any special handling in the delocater? I believe OPENSSL_armcap_P and OPENSSL_ia32cap_P both have special delocate logic handling. Not sure if FIPS is in play for this architecture in question.

Since this change is only updating the implementation of OPENSSL_cpuid_setup so it can be affected by an environment variable, I don't anticipate it having any impact on the delocater. There are no changes to where/how OPENSSL_ppc64le_hwcap2 is stored.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 87.50000% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 77.91%. Comparing base (7ef93cb) to head (18015bf).

Files	Patch %	Lines
crypto/fipsmodule/cpucap/cpu_intel.c	87.50%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1569   +/-   ##
=======================================
  Coverage   77.91%   77.91%           
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  Files         560      560           
  Lines       94629    94638    +9     
  Branches    13620    13621    +1     
=======================================
+ Hits        73729    73740   +11     
+ Misses      20305    20304    -1     
+ Partials      595      594    -1     

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