r260545 cleared the inode flags to fix corruption problems but
we still need to pass some EXT4 flags for the ext4 read-only
mode. None of these attributes has an equivalent in FreeBSD and
are uninteresting for the system utilities so they should be
innaccessible in ext2_getattrib().
Note: we also use EXT4_HUGE_FILE but we use it directly from the
dinode structure so it is not necessary to translate it,
Suggested by: bde
MFC after: 3 days