rc4-hmac implementation

[Sam Hartman]

>>>>> "Steve" == Steve Langasek <vorlon at netexpress.net> writes:

    Steve> des3-hmac-sha is believed more secure than rc4-hmac, but is
    Steve> not supported by Windows.  Windows supports rc4-hmac, but
    Steve> MIT Kerberos does not.  To get strong interoperable crypto,
    Steve> you can use Heimdal, or you might be able to get someone to
    Steve> add support for rc4-hmac to MIT Kerberos if funding was
    Steve> available. :)

I've added rc4 support to MIT Kerberos and committed the code; it is
in our current development snapshots and will be in the 1.3 release.