Revert "Fail build when test fail (#53)" (#62)

Why I did it
In previous PR #53, we fail build when UT fail, it works well in current repo. But UT in sonic-buildimage failed due to redis issue in slave container, which would block submodule update
image

How I did it
Revert previous PR to don't fail build when UT fail for now

Makefile

@@ -49,7 +49,7 @@ $(DHCP6RELAY_TEST_TARGET): $(TEST_OBJS)
 	$(CXX) $(LDFLAGS) $^ $(LDLIBS) $(LDLIBS_TEST) -o $@
 
 test: $(DHCP6RELAY_TEST_TARGET)
-	sudo ASAN_OPTIONS=detect_leaks=0 ./$(DHCP6RELAY_TEST_TARGET) --gtest_output=xml:$(DHCP6RELAY_TEST_TARGET)-test-result.xml || { echo 'Tests failed'; exit 1; }
+	sudo ASAN_OPTIONS=detect_leaks=0 ./$(DHCP6RELAY_TEST_TARGET) --gtest_output=xml:$(DHCP6RELAY_TEST_TARGET)-test-result.xml || true
 	$(GCOVR) -r ./ --html --html-details -o $(DHCP6RELAY_TEST_TARGET)-code-coverage.html
 	$(GCOVR) -r ./ --xml-pretty -o $(DHCP6RELAY_TEST_TARGET)-code-coverage.xml