[krbdev.mit.edu #593] key schedule alignment

[Ken Raeburn via RT]

I believe this is not a problem any more.  We haven't noticed any
problems on a couple of 64-bit platforms.  The key schedule data
structure was changed a while back, which may have improved things. 
Even if not, I think it's the responsibility of the callers of these
functions, and the compiler, to ensure that the key schedule structures
are properly aligned.