Avoid gcc-12 compile warnings.

[bryce-shang]

Issues:

#487

Description of changes:

This PR fixed below warnings reported by gcc-12 on x86-64. Both warnings are false-positive.

Warning 1

In function 'memset',
    inlined from 'OPENSSL_memset' at /home/ubuntu/aws-lc/crypto/x509v3/../internal.h:845:10,
    inlined from 'ipv6_from_asc' at /home/ubuntu/aws-lc/crypto/x509v3/v3_utl.c:1285:9,
    inlined from 'x509v3_a2i_ipadd' at /home/ubuntu/aws-lc/crypto/x509v3/v3_utl.c:1194:14,
    inlined from 'X509_check_ip_asc' at /home/ubuntu/aws-lc/crypto/x509v3/v3_utl.c:1114:21:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:59:10: error: '__builtin_memset' forming offset 16 is out of the bounds [0, 16] of object 'ipout' with type 'unsigned char[16]' [-Werror=array-bounds]
   59 |   return __builtin___memset_chk (__dest, __ch, __len,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   60 |                                  __glibc_objsize0 (__dest));
      |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/ubuntu/aws-lc/crypto/x509v3/v3_utl.c: In function 'X509_check_ip_asc':
/home/ubuntu/aws-lc/crypto/x509v3/v3_utl.c:1109:19: note: 'ipout' declared here
 1109 |     unsigned char ipout[16];
      |                   ^~~~~

Warning 2

ubuntu/aws-lc/crypto/fipsmodule/bcm.c
In function 'SHA224_Final':
cc1: error: writing 4 bytes into a region of size 0 [-Werror=stringop-overflow=]
In file included from /home/ubuntu/aws-lc/crypto/fipsmodule/bcm.c:131:
/home/ubuntu/aws-lc/crypto/fipsmodule/sha/sha256.c:194:26: note: at offset 28 into destination object 'out' of size [0, 28]
  194 | int SHA224_Final(uint8_t out[SHA224_DIGEST_LENGTH], SHA256_CTX *ctx) {
      |                  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Call-outs:

• The compile warnings were reported when building with DCMAKE_BUILD_TYPE=Release.
• CryptoAlg-1100 is created to add gcc-12 into CI.
• Below suppression does not work.

# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wstringop-overflow"

Testing:

source tests/ci/common_posix_setup.sh

# echo "Testing AWS-LC in release mode."
build_and_test -DCMAKE_BUILD_TYPE=Release

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