Add buildx history command

These commands allow working with build records
of completed and running builds.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/pkg/browser/browser_netbsd.go

@@ -0,0 +1,14 @@
+package browser
+
+import (
+	"errors"
+	"os/exec"
+)
+
+func openBrowser(url string) error {
+	err := runCmd("xdg-open", url)
+	if e, ok := err.(*exec.Error); ok && e.Err == exec.ErrNotFound {
+		return errors.New("xdg-open: command not found - install xdg-utils from pkgsrc(7)")
+	}
+	return err
+}