Fix crash in wxDataViewProgressRenderer in non-Unicode build.

We can't use the column pointer in wxDataViewProgressRenderer ctor as it's not
set yet, so postpone setting the renderer label until later in non-Unicode
build which needs the font used by this column to do the conversion to UTF-8.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@68145 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/dvrenderers.h

@@ -185,9 +185,17 @@ public:
     virtual wxSize GetSize() const;
 
 private:
+    void GTKSetLabel();
+
     wxString    m_label;
     int         m_value;
 
+#if !wxUSE_UNICODE
+    // Flag used to indicate that we need to set the label because we were
+    // unable to do it in the ctor (see comments there).
+    bool m_needsToSetLabel;
+#endif // !wxUSE_UNICODE
+
 protected:
     DECLARE_DYNAMIC_CLASS_NO_COPY(wxDataViewProgressRenderer)
 };