With allow_weak_crypto=false, set_default_enctype_var() (helper
function for krb5_set_default_tgs_enctypes(), etc.) was rejecting any
application-provided enctype list that contained any weak enctype even
when valid strong enctypes were present. This broke some Samba
things. Filter the weak enctypes instead. Add test cases.
Reported to Debian by Holger Isenberg. (Debian bug #566977)
Thanks to Simo Sorce for testing.
Commit By: tlyu