TiDB protobuf files

• Can be downloaded at https://github.com/google/protobuf

• go get -u github.com/gogo/protobuf/protoc-gen-gofast
• cd $GOPATH/src/github.com/gogo/protobuf
• git checkout v0.5
• rm $GOPATH/bin/protoc-gen-gofast
• go get github.com/gogo/protobuf/protoc-gen-gofast

We generate all go code in pkg folder and rust in src folder.

• make