Merge pull request #3701 from yang-g/unreachable

include/grpc/support/port_platform.h

src/core/channel/client_channel.c

src/core/client_config/uri_parser.c

src/core/httpcli/parser.c

src/core/iomgr/tcp_client_posix.c

src/core/iomgr/tcp_server_posix.c

src/core/surface/byte_buffer.c

src/core/surface/call.c

src/core/surface/channel_connectivity.c

src/core/surface/completion_queue.c

src/core/transport/chttp2/frame_data.c

src/core/transport/chttp2/frame_goaway.c

src/core/transport/chttp2/hpack_parser.c

src/core/transport/chttp2/parsing.c

src/core/transport/chttp2/stream_encoder.c

src/cpp/server/server.cc