Fix portability for AlmaLinux 8 / manylinux_2_28 (gcc 8)

[thananon]

Summary

gcc 8.5 (AlmaLinux 8 base, used by manylinux_2_28) is older than what Ubuntu 22.04 ships and doesn't pull in some headers transitively or expose std::filesystem from the default libstdc++. This PR makes TransferBench actually build on those toolchains.

• Drop unused #include <barrier> from src/header/TransferBench.hpp. <barrier> is C++20 and requires libstdc++ ≥ 10. std::barrier was never used.
• Add explicit #include <iomanip>, <numeric>, <limits> to Utilities.hpp, NicPeerToPeer.hpp, AllToAll.hpp, AllToAllN.hpp. Older libstdc++ doesn't pull these in via other standard headers.
• Link libstdc++fs unconditionally for std::filesystem. gcc < 9 ships it as a separate static archive in a gcc-private libdir (e.g. /usr/lib/gcc/x86_64-redhat-linux/8/libstdc++fs.a), which CMake's find_library does not search. Bare target_link_libraries(... stdc++fs) lets the compiler driver find it. On gcc 9+ it resolves to a no-op stub archive shipped for compatibility, so it's harmless elsewhere.

Context

This is the portability slice of the original #260, split out so it can land independently. A follow-up PR will add the GitHub Actions workflow + build_packages_local.sh for building relocatable packages against TheRock SDK on top of these fixes.

Test plan

• Reproduced original link/compile failures inside quay.io/pypa/manylinux_2_28_x86_64 (AlmaLinux 8, gcc 8.5)
• Build succeeds inside the same container after this patch
• No effect on the existing Azure DevOps Ubuntu/ROCm CI (changes are toolchain-portability only; on gcc ≥ 9 the stdc++fs link is a no-op and the extra includes are redundant but harmless)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Improve build portability on AlmaLinux 8 / manylinux_2_28 toolchains (gcc 8-era libstdc++) by removing a C++20-only header, adding missing explicit standard-library includes, and ensuring std::filesystem links successfully.

Changes:

• Removed unused C++20 <barrier> include to avoid requiring newer libstdc++ headers.
• Added explicit standard headers (<iomanip>, <numeric>, <limits>) where corresponding facilities are used.
• Updated CMake linking to include stdc++fs for std::filesystem compatibility on older libstdc++.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/header/TransferBench.hpp	Drops unused <barrier> to avoid C++20 dependency.
src/client/Utilities.hpp	Adds <iomanip> needed for manipulators used in table formatting.
src/client/Presets/NicPeerToPeer.hpp	Adds <numeric> for std::iota usage.
src/client/Presets/AllToAll.hpp	Adds <limits> for std::numeric_limits usage.
src/client/Presets/AllToAllN.hpp	Adds <limits> for std::numeric_limits usage.
CMakeLists.txt	Links stdc++fs to support std::filesystem on gcc 8-era libstdc++.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.