[libcxx-commits] [libcxx] [libc++][filesystem] Fix truncation in vformat_string dynamic fallback (PR #203531)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 requested changes to this pull request.

`std::string` always has space for a null terminator, so we don't need to add it additionally.

https://github.com/llvm/llvm-project/pull/203531