ipn/ipnserver: remove Options.AllowQuit.

It was previously used by the MacOS client, but it now does
something different. ipnserver should never obey a client's
request to exit.

Signed-off-by: David Anderson <dave@natulte.net>

cmd/tailscaled/tailscaled.go

@@ -61,7 +61,6 @@ func main() {
 	opts := ipnserver.Options{
 		StatePath:          *statepath,
 		SurviveDisconnects: true,
-		AllowQuit:          false,
 	}
 	err = ipnserver.Run(context.Background(), logf, pol.PublicID.String(), opts, e)
 	if err != nil {

ipn/ipnserver/server.go

@@ -31,7 +31,6 @@ import (
 type Options struct {
 	StatePath          string
 	SurviveDisconnects bool
-	AllowQuit          bool
 }
 
 func pump(logf logger.Logf, ctx context.Context, bs *ipn.BackendServer, s net.Conn) {
@@ -137,11 +136,8 @@ func Run(rctx context.Context, logf logger.Logf, logid string, opts Options, e w
 				bs.Reset()
 				s.Close()
 			}
-			if opts.AllowQuit {
-				os.Exit(0)
-			} else {
+			// Quitting not allowed, just keep going.
 			bs.GotQuit = false
-			}
 		}(ctx, bs, s, i)
 
 		bo.BackOff(ctx, nil)