Avoid side effects in assert expressions

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.)

ticket: 7105

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@25760 dc483132-0cff-0310-8789-dd5450dbe970