Fix AUI compilation without PCH after recent changes.

r65061 broke PCH-less compilation as it used wxClientDC without (forward)
declaring it. Fix this and also correct wxAuiPaneInfo forward declaration.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65072 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/aui/auibar.h

@@ -20,8 +20,8 @@
 #include "wx/sizer.h"
 #include "wx/pen.h"
 
-//class WXDLLIMPEXP_FWD_CORE wxSizerItem;
-class wxAuiPaneInfo;
+class WXDLLIMPEXP_FWD_CORE wxClientDC;
+class WXDLLIMPEXP_FWD_AUI wxAuiPaneInfo;
 
 enum wxAuiToolBarStyle
 {