* path.cc (symlink_info::check_reparse_point): Use NtFsControlFile

	* path.cc (symlink_info::check_reparse_point): Use NtFsControlFile
	to read reparse points.
	(enum shortcut_t): New type.
	(symlink_info::check): Convert sym_check to shortcut_t.  Use shortcut_t
	enum values throughout.  Check reparse point before checking for
	sysfile shortcut.  Open reparse points with READ_CONTROL only to
	accommodate special Vista reparse points.  Add comments.