Let Python build scripts accept both CMAKE_BUILD_TYPE and the oldschool DEBUG and REL_WITH_DEB_INFO variables. (#22875)
Summary:
Currently the build type is decided by the environment variable DEBUG
and REL_WITH_DEB_INFO. This commit also lets CMAKE_BUILD_TYPE be
effective. This makes the interface more consistent with CMake. This
also prepares https://github.com/pytorch/pytorch/issues/22776.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22875
Differential Revision: D16281663
Pulled By: ezyang
fbshipit-source-id: 952f92aad85ff59f1c7abe8256eca8a4a0936026
