Merge github.com:grpc/grpc into max_msg_deadline

BUILD

CMakeLists.txt

Makefile

build.yaml

composer.json

src/compiler/php_generator.cc

src/compiler/php_generator.h

src/compiler/php_generator_helpers.h

src/compiler/php_plugin.cc

src/core/ext/client_channel/connector.c

src/core/ext/client_channel/connector.h

src/core/ext/client_channel/http_connect_handshaker.c

src/core/ext/client_channel/subchannel.c

src/core/ext/transport/chttp2/client/chttp2_connector.c

src/core/ext/transport/chttp2/server/chttp2_server.c

src/core/ext/transport/chttp2/transport/chttp2_transport.c

src/core/lib/channel/handshaker.c

src/core/lib/channel/handshaker.h

src/core/lib/iomgr/endpoint.c

src/core/lib/iomgr/endpoint.h