fix clang compiler warnings for AnalysisBase

Since I finally managed to enable compiler warnings on my machine I went ahead and fixed all reported compiler warnings in AnalysisBase. I skipped the 'keyword-macro' warnings, mostly because those require a more thorough restructuring of the code. I may have potentially broken some things in the Athena/Derivation build, but the easiest way to test is by running the CI.

As I'm not really responsible for most of these packages I tried to be conservative with my fixes. In particular if it complained about an unused class member I usually just commented that class member out instead of removing it. I know that is not best practice, but I'll rather leave the actual removal to the package maintainers.