Force VST_PATH for dssi-vst, fixes loading of projects with it

source/backend/engine/CarlaEngine.cpp

@@ -593,7 +593,16 @@ bool CarlaEngine::addPlugin(const BinaryType btype, const PluginType ptype,
             break;
 
         case PLUGIN_DSSI:
-            plugin = CarlaPlugin::newDSSI(initializer);
+            if (CarlaString(filename).contains("dssi-vst", true))
+            {
+                const ScopedEngineEnvironmentLocker _seel(this);
+                const ScopedEnvVar _sev("VST_PATH", pData->options.pathVST2);
+                plugin = CarlaPlugin::newDSSI(initializer);
+            }
+            else
+            {
+                plugin = CarlaPlugin::newDSSI(initializer);
+            }
             break;
 
         case PLUGIN_LV2: