Rename ext2_dirbadentry() to ext2_check_direntry(). Add directory entry inode value check, and call ext2_check_direntry() in all cases. The dirchk sysctl is removed.
This PR should close next BZ issues:
259024 (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259024)
259041 (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259041)