x86_64 SIMD code is now enabled with compiler pragmas instead of
-m flags (as ARM already was), so the build no longer uses
non-portable compiler flags.
awscrt 0.1.0
Initial implementation: crc32(), crc32c(),
crc64nvme() and their _file() variants, backed
by vendored aws-checksums v1.0.1 and aws-c-common v1.0.3.