test: avoid unnamed parameter in function type template argument

[JohelEGP]

Resolves https://github.com/hsutter/cppfront/commit/212eb15e77bba222c7fda3ff50f1e5f479a627ee#commitcomment-147400224 by avoiding the unnamed parameters, rather than changing the lowering to Cpp1.

[hsutter]

Thanks! There are merge conflicts so I won't try to merge this for 0.8. As described in #1322, that means I need a new one-time CLA that will cover all your future contributions. I've emailed you the new CLA, and one it's completed I can look at this PR.