Add test for correct short/long file names in wxDir.

Verify that enumerating the files using the pattern *.foo doesn't match
*.foo.bar files, as it used to do under MSW.

See #3432.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73836 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775