Fix assert_defined

[cgcgcg]

Motivation

It looks like assert_defined only asserts that the first variable is defined..

[github-actions]

CDash for AT2 results [Currently only accessible from Sandia networks]

[brian-kelley]

@cgcgcg hmm, the tribits function Trilinos/cmake/tribits/core/utils/AssertDefined.cmake is definitely intended to work with multiple arguments. The problem is that it uses a named argument (which takes the first variable name only) instead of variadic ARGV. Your changes here are still correct, but #15132 would let the original code in all the packages work

[cgcgcg]

Closing in favor of #15132 which actually fixes the macro.