Fixes for building with -pedantic

[justsmth]

Issues:

Relates to: aws/aws-lc-rs#425

Description of changes:

• Fix compiler errors that occur when building the "crypto" & "ssl" targets with -pedantic.
• Adds CI jobs gcc-14-pedantic and clang-18-pedantic.

Call-outs:

• This only verifies that the "crypto" and "ssl" targets can be built. These are the two targets required by downstream packages, such as aws-lc-sys.
• The -Wno-c99-c11-compat (GCC) and -Wno-c11-extensions (Clang) are to avoid a pedantic warning related to our use of _Generic:

/home/justsmth/repos/aws-lc/crypto/asn1/../internal.h:1099:4: error: ISO C99 does not support ‘_Generic’ [-Werror=pedantic]
 1099 |   (_Generic((x),                                    \
      |    ^~~~~~~~

• The -Wno-newline-eof is needed b/c Clang complains about a missing newline at the end of the s2n-bignum assembly files:

/home/justsmth/repos/aws-lc/third_party/s2n-bignum/include/_internal_s2n_bignum.h:17:7: warning: no newline at end of file [-Wnewline-eof]
   17 | #endif
      |       ^

• The -Wno-overlength-strings parameter was needed to avoid a failure due to string literals in err-data.c:

...
/tmp/tmp.SO3vhKEAo4/AWS-LC-BUILD/crypto/err_data.c:1603:5: error: string length ‘16178’ is greater than the length ‘4095’ ISO C99 compilers are required to support [-Werror=overlength-strings]
 1603 |     "";
      |     ^~
...

• Building our tests with -pedantic will still fail due largely to our tests using binary literals:

...
Files/crypto_test.dir/endian_test.cc.o -MF crypto/CMakeFiles/crypto_test.dir/endian_test.cc.o.d -o crypto/CMakeFiles/crypto_test.dir/endian_test.cc.o -c /home/justsmth/repos/aws-lc/crypto/endian_test.cc
/home/justsmth/repos/aws-lc/crypto/endian_test.cc:69:20: error: binary constants are a C++14 feature or GCC extension [-Werror]
   69 |   uint32_t value = 0b00000010000000000000000000000;
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/justsmth/repos/aws-lc/crypto/endian_test.cc:70:23: error: binary constants are a C++14 feature or GCC extension [-Werror]
   70 |   uint32_t expected = 0b00100000000000000000000000000;
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/justsmth/repos/aws-lc/crypto/endian_test.cc:84:20: error: binary constants are a C++14 feature or GCC extension [-Werror]
   84 |   uint64_t value = 0b0000001000000000000000000000000000010000000000000000000000;
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

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 78.05%. Comparing base (8258d73) to head (ea5a923).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1608   +/-   ##
=======================================
  Coverage   78.05%   78.05%           
=======================================
  Files         562      562           
  Lines       94600    94600           
  Branches    13575    13575           
=======================================
+ Hits        73840    73842    +2     
+ Misses      20168    20165    -3     
- Partials      592      593    +1     

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[WillChilds-Klein]

do we need distinct CI jobs for pedantry? can we add these flags to existing GCC 13 / clang 18 jobs?

[justsmth]

Supporting a "pedantic" build can be very painful/restrictive. With this PR we are able to compile the "crypto" and "ssl" build targets with -pedantic, but we can't build/run the tests against it.

Since our tests are a better indicator for the health of a build than pedantic warnings, I chose to limit the use of -pedantic here for just helping ensure that downstream consumers aren't blocked b/c they have a build environment that requires -pedantic.

I used only the latest versions of GCC and Clang since those would likely produce a superset of the pedantic warnings from their previous versions.