Remove the mentions of the native OSX wxListCtrl control

This control was removed during the Carbon code removal in commit
5ba67c67e4, so the system option
does nothing now (and was only mentioned in the documentation
and the sample).

interface/wx/sysopt.h

@@ -105,9 +105,6 @@
     @flag{window-default-variant}
         The default variant used by windows (cast to integer from the wxWindowVariant enum).
         Also known as wxWINDOW_DEFAULT_VARIANT.
-    @flag{mac.listctrl.always_use_generic}
-        Tells wxListCtrl to use the generic control even when it is capable of
-        using the native control instead. Also known as wxMAC_ALWAYS_USE_GENERIC_LISTCTRL.
     @flag{mac.textcontrol-use-spell-checker}
         If 1 activates the spell checking in wxTextCtrl.
     @flag{osx.openfiledialog.always-show-types}