Salt for aliases

[Greg Hudson]

On Tue, 2009-04-14 at 12:22 -0400, Sam Hartman wrote:
> I suspect that if you use aliasing for user name aliases that you
> really want to have the KDC return a specific salt string in the
> etype_info2 based on the canonical principal name.

Done and tagged for pullup to 1.7.

Also fixes the salt sent for SALTTYPE_NOREALM keys in the presence of
aliases; previously we were computing the salt based on the requested
name instead of the canonical name.