Added AppTraits for OS/2.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@23791 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/apptrait.h

@@ -138,6 +138,8 @@ public:
     #include "wx/unix/apptbase.h"
 #elif defined(__WXMAC__)
     #include "wx/mac/apptbase.h"
+#elif defined(__OS2__)
+    #include "wx/os2/apptbase.h"
 #else // no platform-specific methods to add to wxAppTraits
     // wxAppTraits must be a class because it was forward declared as class
     class WXDLLIMPEXP_BASE wxAppTraits : public wxAppTraitsBase