The libc++ test was a subset of the tests in libstdc++. This test moves
the libc++ test into `generic` and somne additional test-cases from
`libstdc++` (specifically the recursive unique_ptr case). It turns out
the libstdc++ formatter supports dereferencing using the "object" or
"obj" names. We could either drop those from the tests or support the
same for libc++. I took the latter approach but don't have strong
opinions on this.
Split out from https://github.com/llvm/llvm-project/pull/146740
074ccde3b0