We had to disable the tests for libc++ <= 15 because the `std::ranges`
functions were not available, yet.
Also, on libc++17 there was still an additional `__fn` struct withing
`ranges::__sort`. The test expectation was updated to use a regular
expression, so we can match both the old and the new name.
See
https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/lldb-cmake-matrix/912/execution/node/107/log/