(path_types): Define PATH_NO_ACCESS_CHECK == PC_NO_ACCESS_CHECK.
* path.cc (symlink_info::check_sysfile): Move to symlink_info class and
eliminate arguments that are part of class. Use set_error.
(symlink_info::check_shortcut): Ditto.
(symlink_info::set_error): New function.
(path_conv::check): Pass PC_NO_ACCESS_CHECK to symlink_info::check.
(symlink_info::check): Preserve PC_NO_ACCESS_CHECK in pflags. Use set_error.