[Tests][MapKit/PinAnnotationView] Changed assertion of PinTintColor property to work on other language than English (#6463)

Ensure that assertion is done to a know value to reduce the change of the test failing in case of a device being configured in a diff locale. 

Fixes issue $4114

tests/monotouch-test/MapKit/PinAnnotationViewTest.cs

@@ -80,7 +80,7 @@ namespace MonoTouchFixtures.MapKit {
 				Assert.That (av.PinColor, Is.EqualTo (MKPinAnnotationColor.Red), "PinColor");
 #if MONOMAC
 				if (TestRuntime.CheckSystemVersion (PlatformName.MacOSX, 10, 12)) {
-					Assert.That (av.PinTintColor.ToString (), Is.EqualTo ("Developer/systemRedColor"), "PinTintColor");
+					Assert.That (av.PinTintColor, Is.EqualTo (NSColor.SystemRedColor), "PinTintColor");
 				} else {
 					Assert.Null (av.PinTintColor, "PinTintColor"); // differs from the other init call
 				}