Removed dead code after merge breaking the build

indra/newview/llinventorygallery.cpp

@@ -2409,8 +2409,6 @@ void LLInventoryGallery::startDrag()
             ids.push_back(selected_id);
         }
     }
-    // We must have set this for some reason, but it's causing compile errors
-    (void)src;
     LLToolDragAndDrop::getInstance()->beginMultiDrag(types, ids, LLToolDragAndDrop::SOURCE_AGENT);
 }