1. Don't draw our own custom label if we don't have custom foreground colour,

1. Don't draw our own custom label if we don't have custom foreground colour,
   we don't need to do it then as it works just fine by default then

2. Use the theme font for the label (doesn't do anything for the default Luna
   theme but helps a lot with custom themes, unfortunately metrics are still
   wrong with them)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@44047 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775