posix_spawn_file_actions_addfchdir

posix_spawn_file_actions_addfchdir is specified in POSIX.1-2024. Draft specification:
https://www.austingroupbugs.net/view.php?id=1208

Gnulib module: —

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib:

This function is missing on many platforms: glibc 2.28, macOS 10.14, FreeBSD 13.0, NetBSD 10.0, OpenBSD 6.7, Minix 3.1.8, AIX 7.1, HP-UX 11.31, Solaris 11.4, Cygwin 3.4.6, mingw, MSVC 14, Android API level 33.

Note: Gnulib has a module posix_spawn_file_actions_addfchdir that provides equivalent functionality, just without the suffix _np.