[monotouch-test] Ignore tests that require the GC to actually work in Mac Catalyst.

tests/monotouch-test/CoreAnimation/LayerTest.cs

@@ -107,6 +107,9 @@ namespace MonoTouchFixtures.CoreAnimation {
 		static int TextLayersDisposed;
 		static int Generation;
 		[Test]
+#if __MACCATALYST__
+		[Ignore ("https://github.com/dotnet/runtime/issues/47407")] // The GC doesn't collect objects with finalizers
+#endif
 		public void TestBug26532()
 		{
 			TextLayersDisposed = 0;

tests/monotouch-test/ObjCRuntime/RegistrarTest.cs

@@ -2007,6 +2007,9 @@ namespace MonoTouchFixtures.ObjCRuntime {
 			}
 		}
 
+#if __MACCATALYST__
+		[Ignore ("https://github.com/dotnet/runtime/issues/47407")] // The GC doesn't collect objects with finalizers
+#endif
 		[Test]
 		public void BlockCollection ()
 		{

tests/monotouch-test/mono/WeakReferenceTest.cs

@@ -37,6 +37,9 @@ namespace MonoTouchFixtures {
 			TestRuntime.AssertSystemVersion (PlatformName.MacOSX, 10, 9, throwIfOtherPlatform: false);
 		}
 
+#if __MACCATALYST__
+		[Ignore ("https://github.com/dotnet/runtime/issues/47407")] // The GC doesn't collect objects with finalizers
+#endif
 		[Test]
 		public void NoRetainCyclesExpectedTest ()
 		{