[cs] don't disable the whole TestCSharp

disable only the failing test and add a TODO with a note why it was
disabled

tests/unit/Test.hx

@@ -270,7 +270,7 @@ class Test #if swf_mark implements mt.Protect #end {
 			new TestMatch(),
 			#end
 			new TestSpecification(),
-			#if (cs && false)
+			#if cs
 			new TestCSharp(),
 			#end
 			#if java

tests/unit/TestCSharp.hx

@@ -37,6 +37,7 @@ class TestCSharp extends Test
 		eq(i, 40);
 	}
 
+	#if false // TODO: disabled test because of "Arguments and variables of type Void are not allowed" error
 	public function testChecked()
 	{
 		exc(function()
@@ -50,6 +51,7 @@ class TestCSharp extends Test
 			});
 		});
 	}
+	#end
 
 	#if unsafe