cmd/cue: include Go in the version command

We were showing CUE's own module version,
plus all the settings used for its Go build,
but we entirely forgot to include the version of Go used.

For example, a CUE tip build with Go tip now reports:

	$ cue version
	cue version v0.0.0-20230202102539-2293f18bafde

	go version devel go1.21-6d4de4e386 Wed Feb 1 21:31:01 2023 +0000
		  -buildmode exe
		   -compiler gc
		 CGO_ENABLED 1
			  GOARCH amd64
				GOOS linux
			 GOAMD64 v3
				 vcs git
		vcs.revision 2293f18bafde366df4171c78bd6e7029b53429e0
			vcs.time 2023-02-02T10:25:39Z
		vcs.modified false

I chose to put the new line next to the build settings,
as they both relate to how "go build" was run.

This would have helped us to figure out a recent "cue fmt" bug,
as it only happened to reproduce when cmd/cue was built with Go 1.18.

For #1791.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Id6f28ed4a011404a1b87b49b53dc1ad36cd86338
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/549302
Reviewed-by: Paul Jolly <paul@myitcv.io>
Unity-Result: CUEcueckoo <cueckoo@cuelang.org>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>

cmd/cue/cmd/testdata/script/version.txtar

@@ -8,8 +8,9 @@ stdout -count=1 'cue version \(devel\)'
 # Version output with VCS information.
 env CUE_VERSION_TEST_CFG='[{"Key":"vcs","Value":"git"},{"Key":"vcs.revision","Value":"47b7032385cb490fab7d47b89fca36835cf13d39"},{"Key":"vcs.time","Value":"2022-05-10T04:58:46Z"},{"Key":"vcs.modified","Value":"true"}]'
 exec cue version
-[!go1.18] stdout -count=1 'cue version \(devel\) [a-z]+/[a-z]+'
-[go1.18] stdout -count=1 'cue version v0.0.0-20220510045846-47b7032385cb$'
+[!go1.18] stdout -count=1 '^cue version \(devel\) [a-z]+/[a-z]+'
+[go1.18] stdout -count=1 '^cue version v0.0.0-20220510045846-47b7032385cb$'
+[go1.18] stdout -count=1 '^go version (devel )?go1.'
 [go1.18] stdout -count=1 'vcs git'
 [go1.18] stdout -count=1 'vcs\.revision 47b7032385cb490fab7d47b89fca36835cf13d39'
 [go1.18] stdout -count=1 'vcs\.time 2022-05-10T04:58:46Z'

cmd/cue/cmd/version_1.18.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"runtime"
 	"runtime/debug"
 	"time"
 
@@ -77,7 +78,8 @@ func runVersion(cmd *Command, args []string) error {
 		}
 	}
 
-	fmt.Fprintf(w, "cue version %v\n\n", version)
+	fmt.Fprintf(w, "cue version %s\n\n", version)
+	fmt.Fprintf(w, "go version %s\n", runtime.Version())
 	for _, s := range bi.Settings {
 		if s.Value == "" {
 			// skip empty build settings