Update subversion io handling for supporting OS/2.
Update subversion io handling for supporting OS/2.

* subversion/libsvn_subr/io.c
  (file_perms_set): Comment on Windows & OS/2.
  (svn_io_copy_perms, reown_file, get_default_file_perms,
   merge_default_file_perms, io_set_file_perms,
   svn_io_set_file_read_only, svn_io_set_file_read_write,
   svn_io_set_file_executable, svn_io_is_file_executable,
   svn_io_remove_file2, svn_io_file_rename, svn_io_write_version_file,
   svn_io_open_unique_file3): Use the WIN32 code paths on OS/2.

This commit is based on a
Patch by: Paul Smedley <paul{_AT_}smedley.id.au>
(tweaked by me)

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion