This patch adds support for hardware crc for ARM's new 64 bit architecture.
The patch is completely conditionalized on _arch64_
For the moment I have only done the non pipelined version as the hw I have only has 1 crc execute unit.
Some initial benchmarks on terasort give
sw crc: 107 sec
hw crc: 103 sec
The performance improvement is quite small, but this is limited by the fact that I am using early stage hw which is not performant.
I have also built it on x86 and I think the change is fairly safe for other architectures because post conditionalization the src is identical on other architectures.
This is the first patch I have submitted for Hadoop so I would welcome any feedback and help.