Avoid using itertools.permutations in k5test

k5test is only supposed to require Python 2.4, but cross_realms uses
itertools.permutations which is new in 2.6.  Use a list display
instead.

https://github.com/krb5/krb5/commit/2240347dd3cd3f1f9a068a22df037f2428c7bd7f
Commit By: ghudson
Revision: 25592
Changed Files:
U   trunk/src/util/k5test.py