Fix iOS and Android

src/Android/Avalonia.Android/AndroidThreadingInterface.cs

@@ -1,10 +1,10 @@
 using System;
-using System.Reactive.Disposables;
 using System.Threading;
 
 using Android.OS;
 
 using Avalonia.Platform;
+using Avalonia.Reactive;
 using Avalonia.Threading;
 
 using App = Android.App.Application;

src/Android/Avalonia.Android/ChoreographerTimer.cs

@@ -1,11 +1,11 @@
 using System;
 using System.Collections.Generic;
-using System.Reactive.Disposables;
 using System.Threading.Tasks;
 
 using Android.OS;
 using Android.Views;
 
+using Avalonia.Reactive;
 using Avalonia.Rendering;
 
 using Java.Lang;

src/Avalonia.Base/Avalonia.Base.csproj

@@ -52,6 +52,8 @@
     <InternalsVisibleTo Include="Avalonia.Benchmarks, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.X11, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Win32, PublicKey=$(AvaloniaPublicKey)" />
+    <InternalsVisibleTo Include="Avalonia.Android, PublicKey=$(AvaloniaPublicKey)" />
+    <InternalsVisibleTo Include="Avalonia.iOS, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Dialogs, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="Avalonia.Diagnostics, PublicKey=$(AvaloniaPublicKey)" />
     <InternalsVisibleTo Include="DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7" />

src/iOS/Avalonia.iOS/EaglDisplay.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Collections.Generic;
-using System.Reactive.Disposables;
 using Avalonia.OpenGL;
 using Avalonia.Platform;
+using Avalonia.Reactive;
 using OpenGLES;
 
 namespace Avalonia.iOS