Update Third Party lib (http-parser)
nghttpx: Avoid 0-length DATA in HTTP/2 upstream
nghttpx: Refactor http2_data_read_callback
nghttpx: Send RST_STREAM with NO_ERROR when closing upgraded connection
Merge branch 'http_parser' of https://github.com/alagoutte/nghttp2 into alagoutte-http_parser
Merge branch 'alagoutte-http_parser'
nghttpx: Remove misleading logging
nghttpx: Write accesslog when upstream connection is lost for HTTP/2 and SPDY
Add contrib/.gitignore
Add features to logging, client and server port,
time_iso8601 and request_time.
fixed conflict
Merge branch 'LPardue-accesslog_port'
Implement faster formatting for format_iso8601 and format_common_log
nghttpx: Note the conversion made in <VAR>
nghttpx: Make --accesslog-format usage doc help2man friendly

This is unfortunate but help2man behaves badly when there is indented
lines in help messages in commnad-line args.  We removed indentations
to make help2man happy.
nghttpx: Add $pid to --accesslog-format variable

$pid refers to the PID of the running process.
nghttpx: Add $alpn variable to accesslog formatting

$alpn is a variable which represents ALPN identifier of the protocol
which generates the response.
Allow PRIORITY frame at anytime.

Allowing PRIORITY frame at anytime so that PRIORITY frame to idle
stream can create anchor node in dependency tree.  In this change, we
open stream with new NGHTTP2_STREAM_IDLE state, which is linked in
session->closed_stream_head and is treated as if it is closed stream.
One difference is that if the stream is opened, we remove it from
linked list and change the state to the appropriate one.  To O(1)
removal from linked list, we change session->closed_stream_head to
doubly linked list.
Assign default weight if NGHTTP2_MAX_DEP_TREE_LENGTH is exceeded
Make certain type of HEADERS subject to priority

We make following HEADERS under priority control:
* push response HEADERS
* HEADERS submitted by nghttp2_submit_response

Currently, HEADERS submitted by nghttp2_submit_headers is not attached
to stream.  This is because it may be used as non-final response
header and application may submit final response using
nghttp2_submit_response without checking non-final response header
transmission.