Avoid side effects in assert expressions

asserts may be compiled out with -DNDEBUG, so it's wrong to use an
assert expression with an important side effect.

(We also have scores of side-effecting asserts in test programs, but
those are less important and can be dealt with separately.)

https://github.com/krb5/krb5/commit/221cd4a23691601a14500bc00146c265b50bdc94
Commit By: ghudson
Revision: 25760
Changed Files:
U   trunk/src/lib/apputils/net-server.c
U   trunk/src/lib/crypto/krb/cf2.c
U   trunk/src/util/et/com_err.c