Only enable arm64 CRC32 acceleration if the required header files are there

Only enable arm64 CRC32 acceleration if the required header files are there

If the necessary header files are missing, then fio will bomb out when
building on arm64.  So disable the hardware acceleration option in
that case, since it's only performance improvement and not a
functional regression to turn it off.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jens Axboe <axboe@fb.com>