gnu: gogoprotobuf: Consolidate packages.

gnu: gogoprotobuf: Consolidate packages.

* gnu/packages/golang.scm (go-github-com-gogo-protobuf)[arguments]: Adjust
the #:import-path, and skip the tests and build phases.
(go-github-com-gogo-protobuf-protoc-gen-gogo,
go-github-com-gogo-protobuf-gogoproto, go-github-com-gogo-protobuf-proto):
Remove variables.
(go-github-com-libp2p-go-libp2p-crypto, go-github-com-libp2p-go-libp2p-peer,
go-github-com-libp2p-go-libp2p-metrics): Adjust accordingly.
* gnu/packages/ipfs.scm (go-github-com-ipfs-go-ipfs-api, gx, gx-go): Likewise.
* gnu/packages/syncthing.scm (syncthing): Likewise.