ssl and kerberos

[Vincent Béron]

I need some help with configure.ac.

In RH8 and 9, openssl is compiled with krb5 support. The problem comes
from the fact that the kerberos files are not under /usr/include, rather
/usr/kerberos/include. So when ssl.h includes krb5.h, it can't find it.
It'd need to be detected and add /usr/kerberos/include to the list of
EXTRAINCL if compiling with only ssl.h is not enough.

(I never noticed before because I had recompiled openssl locally to not
use kerberos at all, and on the other machine I never looked that
closely as everything is installed stock)

Once that is fixed, it will trigger another bug in the kerberos part of
openssl, namely that FAR is used, but we'll get to that bridge another
time.

Vincent