UFS improvements
* fs/ufs.c (INODE_NBLOCKS): new definition
(struct grub_ufs_dirent): added fields for non-BSD dirents
(grub_ufs_get_file_block): fixed double indirect handling
(grub_ufs_lookup_symlink): use more robust way to determine whether
symlink is inline
(grub_ufs_find_file): support for non-BSD dirents
(grub_ufs_dir): support for non-BSD dirents