The code in test_makefile was attempting to ignore any
non-interesting files, but missed some corners:
1. There is never a *file* called `__pycache__`.
2. A directory containing only a `__pycache__` subdirectory should be
ignored.
3. A directory containing only hidden files should be ignored.
Simplify this all into a couple of filters that let us check for empty
lists.
Remove wheeldata from both sides of the `assertEqual`, so that we're
*actually* ignoring it from the test set.
This test is only making assertions about the source tree, no code is
being executed that would do anything different based on the value of
`WHEEL_PKG_DIR`.
It's possible to build Python with option `--with-wheel-pkg-dir`
pointing to a custom wheel directory. Don't include the directory in the test
set if the wheels are used from a different location.
Co-authored-by: Miro Hrončok <miro@hroncok.cz>
