Previously we have uint16_t as state member variable in
nghttp2_huff_decode structure to express -1 as failure. This is
because we have 256 valid states. However, we can express failed
state using flags member variable and make state uint8_t. This commit
does this and as a result the size of decoding table is reduced.
* Use 1 Huffman code table for both request and response
* Remove complicated deflater side table size management
* Add encoding context update
* Fix memory leak in inflater
Tatsuhiro Tsujikawa