Add C# support for void *VOID_INT_PTR member variables

Issue reported by Carlos Frederico Biscaya on swig-user mailing list.

Examples/test-suite/csharp/director_void_runme.cs

@@ -67,6 +67,12 @@ public class runme
       if (x != 1334)
         throw new Exception("Bad4 should be 1334, got " + x);
     }
+    {
+      MemberVoid mv = new MemberVoid();
+      global::System.IntPtr zero = global::System.IntPtr.Zero;
+      mv.memberVariable = zero;
+      zero = mv.memberVariable;
+    }
   }
 }
 

Examples/test-suite/director_void.i

@@ -43,5 +43,9 @@ struct Caller {
     return *(int *)p;
   }
 };
+
+struct MemberVoid {
+  void *memberVariable;
+};
 %}