concantenate LICENSE files when building a wheel (#51634)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/50695
I checked locally that the concatenated license file appears at `torch-<version>.dist-info/LICENSE` in the wheel.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51634
Reviewed By: zhangguanheng66
Differential Revision: D26225550
Pulled By: walterddr
fbshipit-source-id: 830c59fb7aea0eb50b99e295edddad9edab6ba3a
