MINOR: hpack: implement the HPACK Huffman table decoder

The code was borrowed from the HPACK experimental implementations
available here :

    https://github.com/wtarreau/http2-exp

It contains the Huffman table as specified in RFC7541 Appendix B, and a
set of reverse tables used to decode a Huffman byte stream, and produced
by contrib/h2/gen-rht. The encoder is not finalized, it doesn't emit the
byte stream but this is not needed for now.
3 files changed