annoying and broken libdes check in configure.in

[Huaqing Zheng]

So, this bit of code in configure.in looks rather broken, at least
when you are building with MIT kerberos.

if test "$with_krb" != "no"; then
dnl Do we need DES for kerberos?
AC_ARG_WITH(krbdes,[  --with-krbdes           use Kerberos DES implementation [
yes]]],
      with_krbdes="$withval", with_krbdes="yes")
if test "$with_krbdes" = "yes"; then
  AC_CHECK_LIB(des,des_ecb_encrypt,
      if test "$with_statickrb" = "yes"; then
          KRB_LIBS="$with_krb/lib/libdes.a"
      else
          KRB_LIBS="-ldes"
      fi,
  AC_MSG_ERROR([The Kerberos DES library is required for Kerberos support.  You
might want --with-auth=unix.]))
fi
fi

First, --with-krbdes is not documented in configure --help  at all.
Second, the with_krbdes defaults to "yes" and does a test link against
libdes, which last existed in kth krb4 but certainly doesn't exist in
in MIT Kerberos 1.3 and newer (not sure if it exists in Heimdal K5).
Also, the error message when the link fails suggests --with-auth=unix,
which is also not documented in configure --help and is probably
obsolete.

Can we just get this entire check ripped out?
-- 
Huaqing Zheng
Beer and Code Wrangler at Large