Release the list of large objects once load() has built the indexes

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/detail/view/image.hpp

@@ -738,6 +738,7 @@ inline void load_image(document_data& d, const std::uint8_t* image, std::size_t
         }
     }
     build_object_indexes(d);
+    std::vector<std::uint32_t>().swap(d.large_objects); // (only needed while building)
     d.discarded = false;
 }