Fix link errors with older MinGW due to use of GetLayout()

This function is not present in older MinGW import libraries, up to at least
MinGW 4.8.1, so we can't use it directly as it was done in
22f0801 and we need to load it dynamically.

(limited backport from commit d55e4b2829b44a07f7c224f7b3327a1267c27093)

src/msw/checklst.cpp

@@ -159,7 +159,7 @@ bool wxCheckListBoxItem::OnDrawItem(wxDC& dc, const wxRect& rc,
     UINT uState = stat & wxOwnerDrawn::wxODSelected ? wxDSB_SELECTED : wxDSB_NORMAL;
 
     // checkmarks should not be mirrored in RTL layout
-    DWORD oldLayout = ::GetLayout(hdc);
+    DWORD oldLayout = impl->GetLayoutDirection() == wxLayout_RightToLeft ? LAYOUT_RTL : 0;
     if ( oldLayout & LAYOUT_RTL )
         ::SetLayout(hdc, oldLayout | LAYOUT_BITMAPORIENTATIONPRESERVED);
     wxDrawStateBitmap(hdc, hBmpCheck, x, y, uState);