Remove KRB5_KDB_FLAG_ALIAS_OK

Remove KRB5_KDB_FLAG_ALIAS_OK

It is simpler and more consistent with Windows to let the KDB module
always return aliases, and use KDC logic (already present) to decide
whether to use the requested or canonical principal name in the
ticket.

With the removal of this flag, "kinit alias" (without the -C flag)
against the LDAP KDB module will issue a ticket for the alias name,
instead of failing with a "client not found" error.

[ghudson@mit.edu: edited comments; wrote commit message]

ticket: 8859 (new)