Restore the use of the correct brush for toolbar background erasing.

The call to SetBrush() was mistakenly removed in r62850 but it is needed
because wxClientDC only inherits background colour but not the brush used by
DrawRectangle() call in wxToolBar::MSWEraseRect(), so the wrong colour was
used under systems < Vista.

Restore this call now.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62922 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/toolbar.cpp

@@ -1835,6 +1835,7 @@ bool wxToolBar::HandlePaint(WXWPARAM wParam, WXLPARAM lParam)
 
     // prepare the DC on which we'll be drawing
     wxClientDC dc(this);
+    dc.SetBrush(GetBackgroundColour());
     dc.SetPen(*wxTRANSPARENT_PEN);
 
     RECT rcUpdate;