goprocess: use debug/buildinfo on Go 1.18 and newer

Use package debug/buildinfo [1] introduced in Go 1.18 [2] when possible.
This should avoid previous issues with rsc.io/goversion where Go
processes were no longer listed.

[1] https://pkg.go.dev/debug/buildinfo
[2] https://go.dev/doc/go1.18#debug/buildinfo

For #102
For #159
For #160

goprocess/gp.go → goprocess/goprocess.go

@@ -9,8 +9,6 @@ import (
 	"os"
 	"sync"
 
-	goversion "rsc.io/goversion/version"
-
 	"github.com/google/gops/internal"
 	ps "github.com/keybase/go-ps"
 )
@@ -119,13 +117,11 @@ func isGo(pr ps.Process) (path, version string, agent, ok bool, err error) {
 	if err != nil {
 		return
 	}
-	var versionInfo goversion.Version
-	versionInfo, err = goversion.ReadExe(path)
+	version, err = goVersion(path)
 	if err != nil {
 		return
 	}
 	ok = true
-	version = versionInfo.Release
 	pidfile, err := internal.PIDFile(pr.Pid())
 	if err == nil {
 		_, err := os.Stat(pidfile)

goprocess/goprocess_1.18.go

@@ -0,0 +1,18 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+// +build go1.18
+
+package goprocess
+
+import "debug/buildinfo"
+
+func goVersion(path string) (string, error) {
+	info, err := buildinfo.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	return info.GoVersion, nil
+}

goprocess/goprocess_lt1.18.go

@@ -0,0 +1,18 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.18
+// +build !go1.18
+
+package goprocess
+
+import goversion "rsc.io/goversion/version"
+
+func goVersion(path string) (string, error) {
+	versionInfo, err := goversion.ReadExe(path)
+	if err != nil {
+		return "", err
+	}
+	return versionInfo.Release, nil
+}