Use some remaining test .cs files from the ios-sources dir in the mono archive

Would be nice to get rid of this, but I don't have time right now.

tests/mono-native/mono-native-mac.csproj.template

@@ -46,13 +46,13 @@
       <Link>MonoNativeConfig.cs</Link>
     </Compile>
     <Compile Include="NativePlatformConfig.cs" />
-    <Compile Include="..\..\external\mono\mcs\class\corlib\Test\Mono\MonoNativePlatform.cs">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\corlib\Test\Mono\MonoNativePlatform.cs">
       <Link>MonoNativePlatform.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\corlib\Test\Mono\MonoNativePlatformType.cs">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\corlib\Test\Mono\MonoNativePlatformType.cs">
       <Link>MonoNativePlatformType.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\corlib\Test\Mono\NativePlatformTest.cs">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\corlib\Test\Mono\NativePlatformTest.cs">
       <Link>NativePlatformTest.cs</Link>
     </Compile>
   </ItemGroup>

tests/mono-native/mono-native.csproj.template

@@ -173,13 +173,13 @@
     <Compile Include="AppDelegate.cs" />
     <Compile Include="NativePlatformConfig.cs" />
     <Compile Include="Introspection.cs" />
-    <Compile Include="..\..\external\mono\mcs\class\corlib\Test\Mono\MonoNativePlatform.cs">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\corlib\Test\Mono\MonoNativePlatform.cs">
       <Link>MonoNativePlatform.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\corlib\Test\Mono\MonoNativePlatformType.cs">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\corlib\Test\Mono\MonoNativePlatformType.cs">
       <Link>MonoNativePlatformType.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\corlib\Test\Mono\NativePlatformTest.cs">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\corlib\Test\Mono\NativePlatformTest.cs">
       <Link>NativePlatformTest.cs</Link>
     </Compile>
     <Compile Include="..\common\MonoNativeConfig.cs">

tests/monotouch-test/monotouch-test.csproj

@@ -171,22 +171,22 @@
     </Compile>
     <Compile Include="..\..\tests\test-libraries\TrampolineTest.generated.cs" />
     <Compile Include="..\..\tests\test-libraries\RegistrarTest.generated.cs" />
-    <Compile Include="..\..\external\mono\mcs\class\System.Drawing\Test\System.Drawing\TestPoint.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\System.Drawing\Test\System.Drawing\TestPoint.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
       <Link>System.Drawing\TestPoint.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\System.Drawing\Test\System.Drawing\TestPointF.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\System.Drawing\Test\System.Drawing\TestPointF.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
       <Link>System.Drawing\TestPointF.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\System.Drawing\Test\System.Drawing\TestRectangle.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\System.Drawing\Test\System.Drawing\TestRectangle.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
       <Link>System.Drawing\TestRectangle.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\System.Drawing\Test\System.Drawing\TestRectangleF.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\System.Drawing\Test\System.Drawing\TestRectangleF.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
       <Link>System.Drawing\TestRectangleF.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\System.Drawing\Test\System.Drawing\TestSize.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\System.Drawing\Test\System.Drawing\TestSize.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
       <Link>System.Drawing\TestSize.cs</Link>
     </Compile>
-    <Compile Include="..\..\external\mono\mcs\class\System.Drawing\Test\System.Drawing\TestSizeF.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
+    <Compile Include="..\..\builds\mono-ios-sdk-destdir\ios-sources\mcs\class\System.Drawing\Test\System.Drawing\TestSizeF.cs" Condition="$(TargetFrameworkIdentifier) != 'Xamarin.WatchOS'">
       <Link>System.Drawing\TestSizeF.cs</Link>
     </Compile>
     <Compile Include="..\api-shared\ObjCRuntime\RegistrarTest.cs">