ipn/ipnlocal, net/dns: use slices.Equal to simplify code (#16641)

Signed-off-by: jishudashu <979260390@qq.com>

ipn/ipnlocal/local.go

@@ -2166,7 +2166,7 @@ func (b *LocalBackend) setWgengineStatus(s *wgengine.Status, err error) {
 	es := b.parseWgStatusLocked(s)
 	cc := b.cc
 	b.engineStatus = es
-	needUpdateEndpoints := !endpointsEqual(s.LocalAddrs, b.endpoints)
+	needUpdateEndpoints := !slices.Equal(s.LocalAddrs, b.endpoints)
 	if needUpdateEndpoints {
 		b.endpoints = append([]tailcfg.Endpoint{}, s.LocalAddrs...)
 	}
@@ -2192,18 +2192,6 @@ func (b *LocalBackend) broadcastStatusChanged() {
 	b.statusLock.Unlock()
 }
 
-func endpointsEqual(x, y []tailcfg.Endpoint) bool {
-	if len(x) != len(y) {
-		return false
-	}
-	for i := range x {
-		if x[i] != y[i] {
-			return false
-		}
-	}
-	return true
-}
-
 // SetNotifyCallback sets the function to call when the backend has something to
 // notify the frontend about. Only one callback can be set at a time, so calling
 // this function will replace the previous callback.