gnu: Remove the various Go union meta-packages.

gnu: Remove the various Go union meta-packages.

* gnu/packages/golang.scm (go-github-com-gogo-protobuf-union,
go-golang-org-x-crypto-union): Remove variables.
(go-golang-org-x-crypto-bcrypt, go-golang-org-x-crypto-blowfish,
go-golang-org-x-crypto-pbkdf2, go-golang-org-x-crypto-tea,
go-golang-org-x-crypto-xtea, go-golang-org-x-crypto-salsa20,
go-golang-org-x-crypto-twofish,)[arguments]: Remove obsolete
'make-gzip-archive-writable' phase.
(go-golang-org-x-crypto-ed25519)[arguments]: The phase
'make-gzip-archive-writable' belongs here now.
(go-github-com-multiformats-go-multihash)[native-inputs]: Remove
go-golang-org-x-crypto-union. Add go-golang-org-x-crypto-blake2s and
go-golang-org-x-crypto-sha3.
(go-github-com-libp2p-go-libp2p-peer)[native-inputs]: Remove
go-golang-org-x-crypto-union. Add go-golang-org-x-crypto-blake2s,
go-golang-org-x-crypto-ed25519, and go-golang-org-x-crypto-sha3.
(go-github-com-libp2p-go-libp2p-metrics)[native-inputs]: Remove
go-golang-org-x-crypto-union. Add go-golang-org-x-crypto-sha3,
go-golang-org-x-crypto-ed25519, and go-golang-org-x-crypto-blake2s.
(go-github-com-multiformats-go-multiaddr)[native-inputs]: Remove
go-golang-org-x-crypto-union. Add go-golang-org-x-crypto-sha3 and
go-golang-org-x-crypto-blake2s.
(go-github-com-multiformats-go-multiaddr-net)[native-inputs]: Remove
go-golang-org-x-crypto-union. Add go-golang-org-x-crypto-sha3 and
go-golang-org-x-crypto-blake2s.
* gnu/packages/ipfs.scm (go-github-com-ipfs-go-ipfs-api)[native-inputs]: Remove
go-golang-org-x-crypto-union. Add go-golang-org-x-crypto-blake2s,
go-golang-org-x-crypto-ed25519, and go-golang-org-x-crypto-sha3.
(gx)[native-inputs]: Remove go-golang-org-x-crypto-union. Add
go-golang-org-x-crypto-blake2s, go-golang-org-x-crypto-ed25519, and
go-golang-org-x-crypto-sha3.
(gx-go)[native-inputs]: Remove go-golang-org-x-crypto-union. Add
go-golang-org-x-crypto-blake2s, go-golang-org-x-crypto-ed25519, and
go-golang-org-x-crypto-sha3.
* gnu/packages/syncthing.scm: Remove go-golang-org-x-text-union,
go-golang-org-x-net-union, and go-github-com-vitrun-qart-union.