aarch64: refactor HW ARM CRC32c detection

aarch64: refactor HW ARM CRC32c detection

- Tweak how fio does the configure probe for hardware accelerated ARM
  CRC32c
- Move the Linux specific runtime detection into os-linux.h making it
  cleaner to implement runtime probing for OSes other than Linux in the
  future
- Make the ARCH_HAVE_CRC_CRYPTO define go into the config-host.* files
  the same way as most other configure defines
- Set/use only the ARCH_HAVE_CRC_CRYPTO define rather than also
  creating/using ARCH_HAVE_ARM64_CRC_CRYPTO

This commit should silence the "Fails to compile: error: sys/auxv.h file
not found" compilation message that was seen on FreeBSD 12/arm64 (but
note a future commit will be required to implement runtime probing and
actually enable the accelerated path on that platform).

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>