pysetup create used to convert package_data from an existing setup.py
into extra_files, but these files are only present in sdists, not
installed: they don?t have the same use case at all, so converting one
into the other did not work.

This moves individual backported functions from compat into a new
_backport.misc module.  compat regains its original purpose of
containing 2to3 support code (i.e. compat for projects using distutils2,
not internal compat for d2 code) and all backports now live under the
private _backport subnamespace.

Also fix the definition of ?any? to bind it to the builtin in 2.5+
(fsencode and detect_encoding not changed, they never exist in
2.x).

This should help avoiding issues like #13170.

Because of implicit relative imports, _backport.tarfile already imported
shutil from the backports instead of the stdlib; I have inlined the only
function it needed to remove the circular dependency between these
modules.

I broke test_mixin2to3 somehow; distutils2-default is okay and packaging too,
so I don?t see an obvious reason right now, I?ll investigate later.

In addition, update the create module to use logging.

- Remove __main__ blocks obsoleted by pysetup
- Fix typo ?seperate?
- Add one test that was promised but not written
- Reorganize one file

This codebase is compatible with 3.1, 3.2 and 3.3.  It was converted with 2to3
and a semi-automated diff/merge with packaging in 3.3 to fix some idioms.
We?ve now come full circle from 2.x to 3.x to 2.x to 3.x again :)

Starting from now, contributors can make patches for packaging (preferred, as
the stdlib?s regrtest is very useful), distutils2 or distutils-python3, and
we?ll make patches flow between versions.