[krbdev.mit.edu #8761] ksu doesn't allow acquisition of non-forwardable tickets

[Greg Hudson via RT]

A ksu -F option seems reasonable, since it already has a -f option.  
Adding a -P option at the same time for symmetry seems appropriate, 
although I don't think proxiable tickets are used with any frequency.

Ticket 7871 would also address this problem on the KDC side.  (But the 
client changes are still valuable due to existing KDCs and other KDC 
implementations.)