Draw shape mask with antialiasing disabled

We need really B/W bitmap to create a mask so antialising should be disabled
in case.

src/osx/nonownedwnd_osx.cpp

@@ -549,6 +549,7 @@ bool wxNonOwnedWindow::DoSetPathShape(const wxGraphicsPath& path)
 
         wxScopedPtr<wxGraphicsContext> context(wxGraphicsContext::Create(dc));
         context->SetBrush(*wxWHITE);
+        context->SetAntialiasMode(wxANTIALIAS_NONE);
         context->FillPath(path);
     }