Remove escape_path in our build system. (#24044)
Summary:
Which was added in https://github.com/pytorch/pytorch/issues/16412.
Also make some CUDNN_* CMake variables to be build options so as to avoid direct reading using `$ENV` from environment variables from CMake scripts.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24044
Differential Revision: D16783426
Pulled By: ezyang
fbshipit-source-id: cb196b0013418d172d0d36558995a437bd4a3986
