Revert "Prevent the user from resizing the last wxDataViewCtrl column"

This reverts commit 24054c95d8 as it
actually should be possible to increase the size of the last column,
even if this shows the horizontal scroll bar.

include/wx/generic/dataview.h

@@ -107,8 +107,6 @@ public:
         return m_flags;
     }
 
-    virtual bool IsResizeable() const wxOVERRIDE;
-
     virtual bool IsSortKey() const wxOVERRIDE
     {
         return m_sort;