Get rid of wxAuiToolBar::m_style and just use base class m_windowStyle.

This fixes an assert exposed by the addition of wxAuiToolBar::Create() in
r72785: as m_style was not initialized before, calling GetWindowStyle() from
wxControl::Create() returned wrong flags.

Fix this by just removing m_style completely, there doesn't seem to be any
need for it nor for overriding GetWindowStyleFlag().

See #13520.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72816 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/aui/auibar.h

@@ -459,8 +459,7 @@ public:
                 const wxSize& size = wxDefaultSize,
                 long style = 0);
 
-    void SetWindowStyleFlag(long style);
-    long GetWindowStyleFlag() const;
+    virtual void SetWindowStyleFlag(long style);
 
     void SetArtProvider(wxAuiToolBarArt* art);
     wxAuiToolBarArt* GetArtProvider() const;
@@ -664,7 +663,6 @@ protected:
     bool m_dragging;
     bool m_gripperVisible;
     bool m_overflowVisible;
-    long m_style;
 
     bool RealizeHelper(wxClientDC& dc, bool horizontal);
     static bool IsPaneValid(long style, const wxAuiPaneInfo& pane);