The same as https://github.com/grpc/grpc-go/pull/2373. Signed-off-by: Yangmin Zhu <ymzhu@google.com>
Implements proposal A18 (https://github.com/grpc/proposal/blob/master/A18-tcp-user-timeout.md). gRPC Core issue for reference: https://github.com/grpc/grpc/issues/15889
ChannelZ is a debugging feature in grpc. It has not had appengine support; this commit removes its support for 1.6, too. This change is because in a recent sys/unix commit 1.6 support was broken.
