On OSX don't propogate the alignment setting from column to renderer if it is a custo...

On OSX don't propogate the alignment setting from column to renderer if it is a custom renderer.  This allows the Render function to deal with the alignment itself and brings the behavior into alignment (pun intended!) with the GTK and generic DV classes.  Fixes #12883

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66706 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775