Stubs for DragDropHelper.

diff --git a/include/Makefile.in b/include/Makefile.in
index 4f18004..4911d2e 100644
--- a/include/Makefile.in
+++ b/include/Makefile.in
@@ -153,6 +153,7 @@
 	wine/obj_dataobject.h \
 	wine/obj_dockingwindowframe.h \
 	wine/obj_dragdrop.h \
+	wine/obj_dragdrophelper.h \
 	wine/obj_enumguid.h \
 	wine/obj_enumidlist.h \
 	wine/obj_errorinfo.h \