llvm-project

3c7727f1 - [libc] Use the dup2 syscall wrapper in posix_spawn (#207879)

[libc] Use the dup2 syscall wrapper in posix_spawn (#207879) posix_spawn's local dup2 helper fell back to a bare dup3 on targets without SYS_dup2. dup3 fails with EINVAL when oldfd == newfd, where dup2 must instead return oldfd if it is valid, so posix_spawn_file_actions_adddup2 with equal fds misbehaved on those targets. linux_syscalls::dup2 already implements the correct fallback, so call it directly and drop the local helper.