Fixing get_policy_manager error with security disabled

The getter would try to access a policy_manager that is unavailable
when using the VSOMEIP_DISABLE_SECURITY flag.
It now returns an empty policy_manager object.

implementation/runtime/src/application_impl.cpp

@@ -1530,7 +1530,11 @@ std::shared_ptr<configuration> application_impl::get_configuration() const {
 }
 
 std::shared_ptr<policy_manager> application_impl::get_policy_manager() const {
+#ifndef VSOMEIP_DISABLE_SECURITY
     return configuration_->get_policy_manager();
+#endif
+    VSOMEIP_WARNING << __func__ << ": manager is not available when security is disabled.";
+    return {};
 }
 
 diagnosis_t application_impl::get_diagnosis() const {