The Go example requires a plugin to the protocol buffer compiler, so it is not build with all the other examples. See:
https://github.com/golang/protobuf
for more information about Go protocol buffer support.
First, install the Protocol Buffers compiler (protoc).
Then, install the Go Protocol Buffers plugin ($GOPATH/bin must be in your $PATH for protoc to find it):
go get github.com/golang/protobuf/protoc-gen-go
Build the Go samples in this directory with "make go". This creates the following executable files in the current directory:
server/server_go client/client_go
and, one more go file named 'calc.pb.go' in proto directory.