[krbdev.mit.edu #8689] t_path.c build failure with NDEBUG

[Greg Hudson via RT]

I will fix the side-effecting asserts in t_path.c.

We unfortunately have hardcoded ports in a bunch of places in our test 
suite, and just haven't done the work of fixing them.  Fixing them 
without a race condition would be somewhat difficult in the various 
places where we stand up a KDC, but simply checking ahead of time for 
an unused port might not be too hard.  Another option we have 
considered is wrapping all client/server tests with cwrap.  This change 
would come at some cost, in that we might not detect bugs which 
manifest in a real network stack and not cwrap's implementation, but 
would have the benefit that we wouldn't be listening on the potentially 
open Internet during test runs.