[libc-commits] [libc] Reland "[libc] Implement clone(2) and use it in thread spawning" (PR #225384)

[Alexey Samsonov via libc-commits]

https://github.com/vonosmas approved this pull request.

LGTM (RISC-V fixup looks good)

https://github.com/llvm/llvm-project/pull/225384