Omit signedpath if no_auth_data_required is set

The no_auth_data_required bit was introduced to suppress PACs in
service tickets when the back end supports them.  Make it also
suppress AD-SIGNEDPATH, so that the ~70-byte expansion of the ticket
can be avoided for services which aren't going to do constrained
delegation.

ticket: 7697 (new)
Portable transport enumerator
Build support for HTTPS transport
Remaining cm_{set,unset}_{read,write} functions
MS-KKDCPP ASN.1 encoding/extraction
HTTPS transport (Microsoft KKDCPP implementation)