[clang-tidy] Fix check for trivially copyable types in modernize-pass-by-value

Summary:
rL270567 excluded trivially copyable types from being moved by
modernize-pass-by-value, but it didn't exclude references to them.
Change types used in the tests to not be trivially copyable.

Reviewers: madsravn, aaron.ballman, alexfh

Subscribers: JDevlieghere, cfe-commits

Differential Revision: https://reviews.llvm.org/D28614

llvm-svn: 291796