nghttpx: Fix crash on http2/client proxy mode
nghttpx: Fix crash on http2/client proxy mode

serioussam/nghttp2,serioussam/nghttp2,thinred/nghttp2,serioussam/nghttp2,serioussam/nghttp2,thinred/nghttp2,icing/nghttp2,wzyboy/nghttp2,wzyboy/nghttp2,thinred/nghttp2,thinred/nghttp2,thinred/nghttp2,serioussam/nghttp2,thinred/nghttp2,thinred/nghttp2,wzyboy/nghttp2,wzyboy/nghttp2,icing/nghttp2,serioussam/nghttp2,icing/nghttp2,icing/nghttp2,serioussam/nghttp2,icing/nghttp2,icing/nghttp2,wzyboy/nghttp2,wzyboy/nghttp2,icing/nghttp2,wzyboy/nghttp2