Re-realize wxAuiToolBar on DPI change to fix its layout

The layout of the toolbar depends on the size of its bitmaps, which
changes when the DPI does, so call Realize() again when this happens.

This fixes the layout of the toolbars in the aui sample when moving it
between screens using different DPI.

include/wx/aui/auibar.h

@@ -642,6 +642,7 @@ protected: // handlers
 
     void OnSize(wxSizeEvent& evt);
     void OnIdle(wxIdleEvent& evt);
+    void OnDPIChanged(wxDPIChangedEvent& evt);
     void OnPaint(wxPaintEvent& evt);
     void OnEraseBackground(wxEraseEvent& evt);
     void OnLeftDown(wxMouseEvent& evt);

src/aui/auibar.cpp

@@ -825,6 +825,7 @@ static wxOrientation GetOrientation(long style)
 wxBEGIN_EVENT_TABLE(wxAuiToolBar, wxControl)
     EVT_SIZE(wxAuiToolBar::OnSize)
     EVT_IDLE(wxAuiToolBar::OnIdle)
+    EVT_DPI_CHANGED(wxAuiToolBar::OnDPIChanged)
     EVT_ERASE_BACKGROUND(wxAuiToolBar::OnEraseBackground)
     EVT_PAINT(wxAuiToolBar::OnPaint)
     EVT_LEFT_DOWN(wxAuiToolBar::OnLeftDown)
@@ -2383,6 +2384,11 @@ void wxAuiToolBar::OnIdle(wxIdleEvent& evt)
     evt.Skip();
 }
 
+void wxAuiToolBar::OnDPIChanged(wxDPIChangedEvent& WXUNUSED(event))
+{
+    Realize();
+}
+
 void wxAuiToolBar::UpdateWindowUI(long flags)
 {
     if ( flags & wxUPDATE_UI_FROMIDLE )