tests: do not depend on $(BUILT_SOURCES), but on osmo-gbproxy

$(BUILT_SOURCES) is not defined, makes no sense to depend on it.

Change-Id: Iefb7ae1a660891a556cf6bf2e46e1d4440da1683
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 48d6579..8f83fa4 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -36,15 +36,15 @@
 	$(NULL)
 
 if ENABLE_EXT_TESTS
-python-tests: $(BUILT_SOURCES)
+python-tests:
 	$(MAKE) vty-test
 	$(MAKE) ctrl-python-test
 else
-python-tests: $(BUILT_SOURCES)
+python-tests:
 	echo "Not running python-based tests (determined at configure-time)"
 endif
 
-vty-python-test: $(BUILT_SOURCES)
+vty-python-test: $(top_builddir)/src/osmo-gbproxy
 	osmotestvty.py -p $(abs_top_srcdir) -w $(abs_top_builddir) -v
 	osmotestconfig.py -p $(abs_top_srcdir) -w $(abs_top_builddir) -v
 	$(srcdir)/vty_test_runner.py -w $(abs_top_builddir) -v
@@ -53,7 +53,7 @@
 # To update the VTY script from current application behavior,
 # pass -u to vty_script_runner.py by doing:
 #   make vty-transcript-test U=-u
-vty-transcript-test:
+vty-transcript-test: $(top_builddir)/src/osmo-gbproxy
 	osmo_verify_transcript_vty.py -v \
 		-n OsmoGbProxy -p 4246 \
 		-r "$(top_builddir)/src/osmo-gbproxy -c $(top_srcdir)/doc/examples/osmo-gbproxy/osmo-gbproxy.cfg" \
@@ -69,7 +69,7 @@
 	$(MAKE) vty-python-test
 	$(MAKE) vty-transcript-test
 
-ctrl-python-test: $(BUILT_SOURCES)
+ctrl-python-test: $(top_builddir)/src/osmo-gbproxy
 	$(srcdir)/ctrl_test_runner.py -w $(abs_top_builddir) -v
 	rm -f $(top_builddir)/sms.db $(top_builddir)/gsn_restart $(top_builddir)/gtphub_restart_count