Merge pull request #4149 from RosettaCommons/vmullig/fix_clang_build_after_gcc_9_fixes
Fix clang/Mac build after Rocco's fixes for gcc/9.
Rocco's fixes revealed a couple of unused private member variables in a class, which were previously being touched by an explicit copy constructor that has been removed, and which clang now complains about. (Note: this is not meant to be a criticism of Rocco's changes. They were needed, and they revealed a problem previously masked.)