[llvm] [Support] Use std::filesystem::remove_all() in remove_directories() (PR #119146)

[Dmitry Vasilyev via llvm-commits]

slydiman wrote:

> std::filesystem::remove_all(std::filesystem::__cxx11::path const&, std::error_code&)

It seems __cxx11 means c++11, not c++17.

https://github.com/llvm/llvm-project/pull/119146