Ensure that AdjustStaticBoxZOrder is always defined

Fix the build in wxUSE_STATBOX=0 and wxUSE_DRAG_AND_DROP=0 case:
AdjustStaticBoxZOrder() must still be defined as it's also used in
DragAcceptFiles().

Closes https://github.com/wxWidgets/wxWidgets/pull/111

src/msw/window.cpp

@@ -1522,8 +1522,6 @@ void wxWindowMSW::Update()
 // drag and drop
 // ---------------------------------------------------------------------------
 
-#if wxUSE_DRAG_AND_DROP
-
 #if wxUSE_STATBOX
 
 // we need to lower the sibling static boxes so controls contained within can be
@@ -1555,9 +1553,8 @@ static inline void AdjustStaticBoxZOrder(wxWindow * WXUNUSED(parent))
 
 #endif // wxUSE_STATBOX/!wxUSE_STATBOX
 
-#endif // drag and drop is used
-
 #if wxUSE_DRAG_AND_DROP
+
 void wxWindowMSW::SetDropTarget(wxDropTarget *pDropTarget)
 {
     if ( m_dropTarget != 0 ) {
@@ -1572,6 +1569,7 @@ void wxWindowMSW::SetDropTarget(wxDropTarget *pDropTarget)
         m_dropTarget->Register(m_hWnd);
     }
 }
+
 #endif // wxUSE_DRAG_AND_DROP
 
 // old-style file manager drag&drop support: we retain the old-style