bpo-38256: Fix binascii.crc32() when inputs are 4+GiB (GH-32000)
When compiled with `USE_ZLIB_CRC32` defined (`configure` sets this on POSIX systems), `binascii.crc32(...)` failed to compute the correct value when the input data was >= 4GiB. Because the zlib crc32 API is limited to a 32-bit length.
This lines it up with the `zlib.crc32(...)` implementation that doesn't have that flaw.
**Performance:** This also adopts the same GIL releasing for larger inputs logic that `zlib.crc32` has, and causes the Windows build to always use zlib's crc32 instead of our slow C code as zlib is a required build dependency on Windows.
6 files changed
