crc32c: add aarch64 optimized crc32c implementation

crc32c: add aarch64 optimized crc32c implementation

ARMv8 defines a set of optional CRC32/CRC32C instructions.
This patch defines an optimized function that uses these
instructions when available rather than table-based lookup.
Optimized function based on a Hadoop patch by Ed Nevill.

Autotools updated to check for compiler support.
Optimized function is selected at runtime based on HWCAP_CRC32.
Added crc32c "performance" unit test and arch unit test.

Tested on AMD Seattle.
Passes all crc32c unit tests.
Unit test shows ~4x performance increase versus sctp.

Signed-off-by: Yazen Ghannam <yazen.ghannam@linaro.org>
Reviewed-by: Steve Capper <steve.capper@linaro.org>