cannot bind non-const lvalue reference to an rvalue

[pengxutao]

Hello, here is an error in https://github.com/t-taniai/LocalExpStereo/blob/db6e2ad7a02fbbe07dd6f505a34bbf80c82ef871/LocalExpansionStereo/StereoEnergy.h#L625 because Reusable() is a rvalue, which cannot be used to initialize a non-const lvalue reference.