Add build infrastructure for common compares

main.c is shared between both CRC implementations so we
can get accurate measurements.

Adding Makefile because make.
Run a tiny crc before the big crc

Adler uses the first sum request to populate internal
lookup tables.  Don't include initialization time in
the runtime of the sum we're comparing.
Add compare script

Run: ./compare.sh <filename>

Example usage:

matt@ununoctium:~/repos/crc64-compare% ./compare.sh /Users/matt/Downloads/Temp\ Keep/Ed\ Sheeran\ -\ Live\ At\ The\ O2\ London\ .mp4
Filesize: 614M
Asking crc64-redis to sum "/Users/matt/Downloads/Temp Keep/Ed Sheeran - Live At The O2 London .mp4"...
Asking crc64-adler to sum "/Users/matt/Downloads/Temp Keep/Ed Sheeran - Live At The O2 London .mp4"...
Redis CRC-64: e0ff2a57538fa9d4
Adler CRC-64: afc85640d5e35ba9
Adler throughput: 1638.609548 MB/s
Redis throughput: 410.642677 MB/s
Adler is 3.99x faster than Redis

matt@ununoctium:~/repos/crc64-compare% ./compare.sh /Users/matt/Downloads/John\ Mayer\ -\ Live\ At\ Austin\ City\ Limits\ PBS\ -\ Full\ Concert-gcdUz12FkdQ.mp4
Filesize: 731M
Asking crc64-redis to sum "/Users/matt/Downloads/John Mayer - Live At Austin City Limits PBS - Full Concert-gcdUz12FkdQ.mp4"...
Asking crc64-adler to sum "/Users/matt/Downloads/John Mayer - Live At Austin City Limits PBS - Full Concert-gcdUz12FkdQ.mp4"...
Redis CRC-64: ee43263b0a2b6c60
Adler CRC-64: 0a18e3b48368c9d1
Adler throughput: 1637.606863 MB/s
Redis throughput: 401.824009 MB/s
Adler is 4.07x faster than Redis
Add README.md