Windows-specific case insensitive globbing tests fail on Mac OSX

[Martin Packman]

Two tests related to case insensitive globbing in win32utils fail on the Mac babune builders:

<http://babune.ladeuil.net:24842/job/selftest-osx-10.5/41/testReport/bzrlib.tests.test_win32utils/TestWin32UtilsGlobExpand/test_case_insensitive_globbing/>

Traceback (most recent call last):
  ...
  File ".../bzrlib/tests/test_win32utils.py", line 127, in test_case_insensitive_globbing
    [[u'A?'], [u'a1', u'a2']],
  File ".../bzrlib/tests/test_win32utils.py", line 174, in _run_testset
    self.assertEqual(expected, result, 'pattern %s' % pattern)
AssertionError: pattern [u'A?']
not equal:
a = [u'a1', u'a2']
b = [u'A?']

<http://babune.ladeuil.net:24842/job/selftest-osx-10.5/41/testReport/bzrlib.tests.test_win32utils/Test_CommandLineToArgv/test_case_insensitive_globs/>

Traceback (most recent call last):
  ...
  File ".../bzrlib/tests/test_win32utils.py", line 331, in test_case_insensitive_globs
    self.assertCommandLine([u'A/b.c'], 'A/B*')
  File ".../bzrlib/tests/test_win32utils.py", line 289, in assertCommandLine
    self.assertEqual(expected, sorted(argv))
AssertionError: not equal:
a = [u'A/b.c']
b = [u'A/B*']

Basically the globs are not being expanded because the glob module ends up defering to os.path.normcase, which as documented "On Unix and Mac OS X, this returns the path unchanged":
<http://docs.python.org/library/os.path.html#os.path.normcase>

As these are tests for code that will otherwise never be run on non-windows platforms, and doesn't run on other nixes as they don't have the case insensitive filesystem feature, just making the skip clause more accurate is probably the most sensible fix.