Don't force a dependency on nfd

Other compatible forwarders may be used

Change-Id: I0736af1619e3b33ebb7c580928ad9b54f9854f04
diff --git a/ndns/debian/control b/ndns/debian/control
index 0721b66..5d9e8a0 100644
--- a/ndns/debian/control
+++ b/ndns/debian/control
@@ -17,7 +17,8 @@
 
 Package: ndns
 Architecture: i386 amd64 arm64 armel armhf ppc64el
-Depends: ${shlibs:Depends}, ${misc:Depends}, nfd
+Depends: ${shlibs:Depends}, ${misc:Depends}
+Suggests: nfd
 Description: Domain Name Service for Named Data Networking
  NDNS is a completely distributed database system that largely mimics
  the structure of the DNS system in today's Internet but operates within