Fix error when running scenes in Unity Editor on Windows

When the Editor is configured to target Android devices, users can
still run scenes within the Unity Editor, which runs on Windows.

Close #240

Assets/VLCUnity/Internal/OnLoad.cs

@@ -6,7 +6,7 @@ namespace LibVLCSharp
 {
     class OnLoad
     {
-#if UNITY_ANDROID || UNITY_STANDALONE_OSX || UNITY_EDITOR_OSX
+#if !UNITY_EDITOR_WIN && (UNITY_ANDROID || UNITY_STANDALONE_OSX || UNITY_EDITOR_OSX)
         const string UnityPlugin = "libVLCUnityPlugin";
 #elif UNITY_IOS
         const string UnityPlugin = "@rpath/VLCUnityPlugin.framework/VLCUnityPlugin";