nghttp2: bump to 1.40.0

nghttp2: bump to 1.40.0

41060943 Bump up version number to 1.40.0, LT revision to 33:0:19
5ae9bb89 Fail fast if huffman decoding context is in failure state
bb519154 Merge pull request #1413 from nghttp2/check-authority
77f5487a Add nghttp2_check_authority as public API
db9a8f6e Merge pull request #1409 from nghttp2/fix-wrong-stream-close-error-code
6f28a69b Merge pull request #1411 from richard78917/fix_warning
6ce4835e Fix the bug that stream is closed with wrong error code
29042f1c priority_spec::valid(): remove const qualifier from return value
d08c4395 Merge pull request #1405 from nghttp2/huffman
5d6964cf Faster huffman decoding
0d855bfc Faster huffman encoding
6f967c6e Fix errors reported by coverity scan
b8a43db8 Merge pull request #1394 from wrowe/fix-static-libname
70b62c1a Merge pull request #1393 from wrowe/fix-static-msvcrt
28b1f0b9 Avoid filename collision of static and dynamic lib
1dd966f1 Merge branch 'fix-nghttpx-mruby'
fe8946dd nghttpx: Fix bug that mruby is incorrectly shared between backends
72b71a6b Add new flag ENABLE_STATIC_CRT for Windows
f8933fe5 nghttpx: Reconnect h1 backend if it lost connection before sending headers
89c33d69 Update neverbleed
7079dc5e Update neverbleed to fix memory leak
5080db84 Revert "nghttpx: Reconnect h1 backend if it lost connection before sending headers"
053c7ac5 nghttpx: Returns 408 if backend timed out before sending headers
8a59ce6d nghttpx: Reconnect h1 backend if it lost connection before sending headers
f2fde180 Remove redundant null check before delete
95efb3e1 Don't read too greedily
0a6ce87c Add nghttp2_option_set_max_outbound_ack
2aa79fa9 Bump up LT revision to 32:0:18
3980678d Merge branch 'nghttpx-fix-request-stall'
319d5ab1 nghttpx: Fix request stall
448bbbc3 integration-tests: gofmt
e575a2aa Merge pull request #1377 from Aldrog/cmake_systemd
4f7aedc9 cmake: Support building nghttpx with systemd
7a590893 Fix clang-8 warning
ee443134 Fix FPE with default backend
abef9b90 Fix log-level is not set with cmd-line or configuration file
12a999f0 Bump up version number to 1.40.0-DEV
acfb3607 Update manual pages

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>