merge master

CMakeLists.txt

Makefile

README.md

build.yaml

config.m4

doc/negative-http2-interop-test-descriptions.md

include/grpc/impl/codegen/port_platform.h

include/grpc/support/log_windows.h

package.json

src/core/ext/census/tracing.c

src/core/ext/client_channel/http_connect_handshaker.c

src/core/ext/client_channel/http_connect_handshaker.h

src/core/ext/resolver/dns/native/dns_resolver.c

src/core/ext/transport/chttp2/transport/frame_rst_stream.c

src/core/lib/iomgr/iocp_windows.c

src/core/lib/iomgr/tcp_server_windows.c

src/php/bin/generate_proto_php.sh

src/php/ext/grpc/call.c

src/php/ext/grpc/call_credentials.c

src/php/ext/grpc/channel_credentials.c