cmd/tailscale: add "tailscale configure-host" to prep a Synology machine at boot

Updates #3761

Change-Id: Ib5ab9a4808ade074f48d3abee22c57d7670f9e21
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/cli.go

@@ -29,6 +29,7 @@ import (
 	"tailscale.com/paths"
 	"tailscale.com/safesocket"
 	"tailscale.com/syncs"
+	"tailscale.com/version/distro"
 )
 
 var Stderr io.Writer = os.Stderr
@@ -155,6 +156,9 @@ change in the future.
 	if strSliceContains(args, "debug") {
 		rootCmd.Subcommands = append(rootCmd.Subcommands, debugCmd)
 	}
+	if runtime.GOOS == "linux" && distro.Get() == distro.Synology {
+		rootCmd.Subcommands = append(rootCmd.Subcommands, configureHostCmd)
+	}
 
 	if err := rootCmd.Parse(args); err != nil {
 		if errors.Is(err, flag.ErrHelp) {