Let prms denote the result of (m & perms::mask),
where m is determined as if by converting the st_mode member
of the obtained struct stat to the type perms.
Returns: Same as status(), above, except
that if the attributes indicate a symbolic link, as if by POSIX S_ISLNK,
returns file_status(file_type::symlink, prms).
The signature with argument ec returns
file_status(file_type::none) if an error occurs.