Remove old disabled code to support truncated passwords

Remove old disabled code to support truncated passwords

ka_UserAuthenticateGeneral had code disabled with #ifdef OLDCRUFT to
retry failed authentications by truncating the password to eight
characters, with a comment that the truncating behavior of kpasswd
was disabled in 1990.  Nothing references this preprocessor define in
the source tree.  Delete the dead code.

Reviewed-on: http://gerrit.openafs.org/336
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>