ipn/ipnlocal: remove an unnecessary unlock shortcut

The early unlock on this branch was required because the "send" method goes on
to acquire the mutex itself. Rather than release the lock just to acquire it
again, call the underlying locked helper directly.

Updates #11649

Change-Id: I50d81864a00150fc41460b7486a9c65655f282f5
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>

ipn/ipnlocal/local.go

@@ -1501,8 +1501,6 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 		return
 	}
 	if st.Err != nil {
-		// The following do not depend on any data for which we need b locked.
-		unlock.UnlockEarly()
 		if errors.Is(st.Err, io.EOF) {
 			b.logf("[v1] Received error: EOF")
 			return
@@ -1511,7 +1509,7 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 		var uerr controlclient.UserVisibleError
 		if errors.As(st.Err, &uerr) {
 			s := uerr.UserVisibleError()
-			b.send(ipn.Notify{ErrMessage: &s})
+			b.sendToLocked(ipn.Notify{ErrMessage: &s}, allClients)
 		}
 		return
 	}