Fix 'make depend' for out of the source tree build.

diff --git a/configure b/configure
index ee69347..c10b8d1 100755
--- a/configure
+++ b/configure
@@ -7595,6 +7595,7 @@
 dlls/dinput/keyboard \
 dlls/dinput/mouse \
 dlls/kernel/messages \
+dlls/user/dde \
 dlls/user/resources \
 dlls/wineps/data \
 "