(Contributed by Walter Dörwald).

* Convert three test modules to unittest format.
* Expanded coverage in test_structseq.py.
* Raymond added a new test in test_sets.py

nodes (in Parser/node.c) resolves the gross memory consumption
exhibited by the EMX runtime on OS/2, so the test should be exercised
on this platform.

Skip test_longexp for MacPython on Mac OS X. It triggers a pathological realloc slowdown. Some tests with shorter expressions lead me to the conclusion that it will eventually finish, but it may take a few weeks:-)

2.2.1 candidate.

  Lib/
    os.py
    os2emxpath.py   // added - OS/2 EMX specific path manipulation routines
    popen2.py
    site.py
  Lib/test/
    test_fcntl.py
    test_longexp.py

Update the test suite for the changes introduced by the EXTENDED_ARG
opcode.

This closes the regression test changes of SourceForge patch #100893.