Use hardware accelerated CRC32C function if available

[tvoinarovskyi]

@dpkp @jeffwidman Hehe, I'm an idiot for this =) So, here I was pushing my butt to accelerate varint implementation, but did not look properly at the profiler.
Long story short, while accelerating the V2 implementation for aiokafka I found that _crc32c.py is super slow and takes more time for 1 call than 100 append. So as a fast fix I propose to use https://github.com/ICRAR/crc32c if available on the system. I will look into _crc32c.py script later to make it a bit faster.

Benchmark without HW crc32:

.....................
batch_read_v0: Mean +- std dev: 1.42 ms +- 0.03 ms
.....................
batch_read_v1: Mean +- std dev: 1.44 ms +- 0.03 ms
.....................
batch_read_v2: Mean +- std dev: 3.10 ms +- 0.06 ms

With HW crc32:

.....................
batch_read_v0: Mean +- std dev: 1.48 ms +- 0.05 ms
.....................
batch_read_v1: Mean +- std dev: 1.49 ms +- 0.05 ms
.....................
batch_read_v2: Mean +- std dev: 1.09 ms +- 0.04 ms

So now V2 is relatively the same speed as V1 and V0. Now we can move on to TransactionalProducer =)

[jeffwidman]

Oh interesting. Two thoughts:

1. If we go down this route of fixing by adding an optional dependency, there should be a note about it in the docs as an optional way to speedup kafka-python.
2. It's not clear to me what the other options are beyond adding an optional dependency... since this isn't pure python, does that create problems with directly vendoring it in like we do a few other libs?

[tvoinarovskyi]

@jeffwidman Yea, will patch the docs.
Yes, you can't easiely bundle a C extension module, you will need to correctly build it. As for alternitives, in aiokafka I plan to use the C implementation taken from librdkafka...
I will also try to make the python script at least somewhat faster.

[tvoinarovskyi]

@jeffwidman Could you read this through, good enough?

[jeffwidman]

Looks great

[jeffwidman]

LGTM, I held off on merging this @tvoinarovskyi in case you want to make any more changes first... when you're ready please press the green button.

[jeffwidman]

Looks great