generated files: use "go install" to install binaries

[thaJeztah]

Now that this repository moved to go1.16, we can use 'go install' to install these binaries, as mentioned in #2146

Before:

#11 [gobuild-base 4/6] RUN git clone https://github.com/gogo/protobuf.git /go/src/github.com/gogo/protobuf 	&& cd /go/src/github.com/gogo/protobuf 	&& git checkout -q v1.3.2 	&& go install ./protoc-gen-gogo ./protoc-gen-gogofaster ./protoc-gen-gogoslick
#11 0.061 Cloning into '/go/src/github.com/gogo/protobuf'...
#11 DONE 12.7s

#12 [gobuild-base 5/6] RUN git clone https://github.com/golang/protobuf.git /go/src/github.com/golang/protobuf 	&& cd /go/src/github.com/golang/protobuf 	&& git checkout -q v1.3.5 	&& go install ./protoc-gen-go
#12 0.093 Cloning into '/go/src/github.com/golang/protobuf'...
#12 DONE 2.7s

After:

#11 [gobuild-base 4/6] RUN --mount=target=/root/.cache,type=cache GO111MODULE=on go install 	github.com/gogo/protobuf/protoc-gen-gogo@v1.3.2 	github.com/gogo/protobuf/protoc-gen-gogofaster@v1.3.2 	github.com/gogo/protobuf/protoc-gen-gogoslick@v1.3.2
#11 0.200 go: downloading github.com/gogo/protobuf v1.3.2
#11 DONE 7.4s

#12 [gobuild-base 5/6] RUN --mount=target=/root/.cache,type=cache GO111MODULE=on go install 	github.com/golang/protobuf/protoc-gen-go@v1.3.5
#12 0.162 go: downloading github.com/golang/protobuf v1.3.5
#12 DONE 2.3s

[tonistiigi]

nit, but arg should be right before the command that use them. So instead move the protoc/gogo arg to the correct place.

[thaJeztah]

Ah, yes, I can move these to where they're used (there's pros/cons for each; having them at the top allows to view all versions at a glance, so I though that was the intent). I saw the majority was defined at the top, so thought to move it there.

Let me update.

[thaJeztah]

Updated 👍 I also thought PROTOBUF_VERSION=v1.3.5 had to be updated (as previously it was kept in sync with the go.mod), but doing so failed the build;

#16 2.266 util/stack/generate.go
#16 2.271 protoc-gen-go: unable to determine Go import path for "stack.proto"
#16 2.271
#16 2.271 Please specify either:
#16 2.271 	• a "go_package" option in the .proto source file, or
#16 2.271 	• a "M" argument on the command line.
#16 2.271
#16 2.271 See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.
#16 2.271
#16 2.272 --go_out: protoc-gen-go: Plugin failed with status code 1.
#16 2.273 util/stack/generate.go:3: running "protoc": exit status 1

Then I found cfb73e5, so looks like we can't / mustn't (currently) update. 😅

[tonistiigi]

Then I found cfb73e5, so looks like we can't / mustn't (currently) update

Yes, we need to look at that separately