build: fix mess with 'db_test_SOURCES' and 'db_test_LDADD'

Somehow both 'db_test_SOURCES' and 'db_test_LDADD' ended up in
'src/Makefile.am'. This causes automake / autoconf to complain.
Let's get rid of both useless declarations.

Furthermore, the actual 'db_test_LDADD' in 'tests/Makefile.am'
contained references to the source files from '$(top_srcdir)'.
Most likely, the original intention was to depend on the object
files in '$(top_builddir)'. Let's also fix this.

Change-Id: Ib2e436ed91d9b7551dc5b205329d468c2b0ced04
diff --git a/src/Makefile.am b/src/Makefile.am
index 7ee019f..131b44f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -87,21 +87,6 @@
 	$(SQLITE3_LIBS) \
 	$(NULL)
 
-db_test_SOURCES = \
-	auc.c \
-	db.c \
-	db_auc.c \
-	db_test.c \
-	logging.c \
-	rand_fake.c \
-	$(NULL)
-
-db_test_LDADD = \
-	$(LIBOSMOCORE_LIBS) \
-	$(LIBOSMOGSM_LIBS) \
-	$(SQLITE3_LIBS) \
-	$(NULL)
-
 osmo_euse_demo_SOURCES = \
 	osmo-euse-demo.c \
 	$(NULL)
diff --git a/tests/db/Makefile.am b/tests/db/Makefile.am
index afda5be..fa925f8 100644
--- a/tests/db/Makefile.am
+++ b/tests/db/Makefile.am
@@ -26,10 +26,10 @@
 	$(NULL)
 
 db_test_LDADD = \
-	$(top_srcdir)/src/db.c \
-	$(top_srcdir)/src/db_hlr.c \
-	$(top_srcdir)/src/db_auc.c \
-	$(top_srcdir)/src/logging.c \
+	$(top_builddir)/src/logging.o \
+	$(top_builddir)/src/db_auc.o \
+	$(top_builddir)/src/db_hlr.o \
+	$(top_builddir)/src/db.o \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
 	$(LIBOSMOABIS_LIBS) \