osmo-ns-dummy: add ctrl interface

It's handy for rate_ctr tests with follow-up patches.

Related: OS#5671
Change-Id: If6e06d9433e438b92f1ed1ef0f892308e031779b
diff --git a/utils/Makefile.am b/utils/Makefile.am
index 47c5a78..712f01a 100644
--- a/utils/Makefile.am
+++ b/utils/Makefile.am
@@ -35,6 +35,7 @@
 osmo_ns_dummy_LDADD = $(LDADD) $(TALLOC_LIBS) \
 			$(top_builddir)/src/gb/libosmogb.la \
 			$(top_builddir)/src/vty/libosmovty.la \
+			$(top_builddir)/src/ctrl/libosmoctrl.la \
 			$(top_builddir)/src/gsm/libosmogsm.la
 osmo_ns_dummy_CFLAGS = $(TALLOC_CFLAGS)
 endif