Really fix build without liblo

Signed-off-by: falkTX <falktx@falktx.com>

source/backend/plugin/CarlaPluginJack.cpp

@@ -294,7 +294,9 @@ protected:
 
             const ScopedEngineEnvironmentLocker _seel(kEngine);
 
+#ifdef HAVE_LIBLO
             const ScopedEnvVar sev3("NSM_URL", lo_server_get_url(fOscServer));
+#endif
             const ScopedEnvVar sev2("LD_LIBRARY_PATH", libjackdir.buffer());
             const ScopedEnvVar sev1("LD_PRELOAD", ldpreload.isNotEmpty() ? ldpreload.buffer() : nullptr);