__all__ for several more modules

Lib/poplib.py

Lib/posixfile.py

Lib/posixpath.py

Lib/pprint.py

Lib/pre.py

Lib/profile.py

Lib/pstats.py

Lib/pty.py

Lib/py_compile.py

Lib/pyclbr.py

Lib/quopri.py

Lib/test/test___all__.py