Fix typo bug that prevented FILE_DELETE_CHILD from being set

The Windows FILE_DELETE_CHILD right was not being set on directories
when the user had write and execute permission. When translating a
POSIX permission for a specific class, e.g. user, we right shift the
appropriate number of bits, e.g. 6, and then compare using the 'other'
permission contants, e.g. S_IWOTH.