build: recoin db_test as non-installable program

Change-Id: Id21e7cc1d94824af75a5639810c7d61d7fa7964c
diff --git a/src/Makefile.am b/src/Makefile.am
index 3286560..6c6c9e6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -22,6 +22,9 @@
 
 bin_PROGRAMS = \
 	osmo-hlr \
+	$(NULL)
+
+noinst_PROGRAMS = \
 	db_test \
 	$(NULL)