MinGW compilation fix.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@11657 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/univ/themes/win32.cpp

@@ -38,6 +38,11 @@
     #include "wx/scrolbar.h"
     #include "wx/slider.h"
     #include "wx/textctrl.h"
+
+    #ifdef __WXMSW__
+        // for COLOR_* constants
+        #include "wx/msw/private.h"
+    #endif
 #endif // WX_PRECOMP
 
 #include "wx/notebook.h"