Refactor lauch agent utils.

ShadowsocksX-NG/LaunchAgentUtils.swift

@@ -156,8 +156,12 @@ func SyncSSLocal() {
         
         let on = UserDefaults.standard.bool(forKey: "ShadowsocksOn")
         if on {
+            if changed {
                 StopSSLocal()
+            }
             StartSSLocal()
+        } else {
+            StopSSLocal()
         }
     } else {
         removeSSLocalConfFile()
@@ -291,14 +295,17 @@ func SyncPrivoxy() {
         
         let on = UserDefaults.standard.bool(forKey: "LocalHTTPOn")
         if on {
+            if changed {
                 StopPrivoxy()
-            StartPrivoxy()
             }
-     else {
+            StartPrivoxy()
+        } else {
+            StopPrivoxy()
+        }
+    } else {
         removePrivoxyConfFile()
         StopPrivoxy()
     }
-    }
 }
 
 // --------------------------------------------------------------------------------
@@ -429,10 +436,14 @@ func SyncKcptun() {
             
             let on = UserDefaults.standard.bool(forKey: "ShadowsocksOn")
             if on {
+                if changed {
                     StopKcptun()
-                StartKcptun()
-                return
                 }
+                StartKcptun()
+            } else {
+                StopKcptun()
+            }
+            return
         }
     }
     StopKcptun()