bpo-32303 - Consistency fixes for namespace loaders (GH-5481) (#5503)

* Make sure ``__spec__.loader`` matches ``__loader__`` for namespace packages.
* Make sure ``__spec__.origin` matches ``__file__`` for namespace packages.

https://bugs.python.org/issue32303
https://bugs.python.org/issue32305
(cherry picked from commit bbbcf8693b876daae4469765aa62f8924f39a7d2)

Co-authored-by: Barry Warsaw <barry@python.org>
10 files changed