Main directory for fast CRC using pclmulqdq.

crc16f - non-reflected 16 bit CRC code
crc16r - reflected 16 bit CRC code
crc32f - non-reflected 32 bit CRC code
crc32r - reflected 32 bit CRC code
crc64f - non-reflected 64 bit CRC code
crc64r - reflected 64 bit CRC code
crz64f - non-reflected 64 bit CRC code avx512
crz64r - reflected 64 bit CRC code avx512