Revisiting the case for CMake as a primary, cross-major-plats, build config

[erlendaasland (Erlend E. Aasland)]

FTR:

• bpo-40743: [CMake] It’s 2020, where is CMake?
• Is there prior discussion around the build system of CPython itself?
• GitHub - python-cmake-buildsystem/python-cmake-buildsystem: A cmake buildsystem for compiling Python