[krbdev.mit.edu #5662] KDC stash endian independence

[Ken Raeburn via RT]

We're probably going to be replacing the stash file with a keytab in the not too distant future.

If you're already deploying this code, our conversion code will need to cope with it.

If we want to move stash files between architectures of different byte orders and then convert, 
we should have non-conditionalized code that figures out the stash file's byte order and 
converts as necessary.