Summary:
Adds bzip2 support to `folly/io/Compression.h`.
Adds bzip2 to the default set of supported codecs for the `AutomaticCodec`.

Reviewed By: yfeldblum

Differential Revision: D4873771

fbshipit-source-id: d4f4861aef7e4b9efb67095e8892c265b5ae5557