pidfd_getpid
------------

Documentation:

  * Querying a Process (libc),

  * https://lwn.net/Articles/943022/.

Gnulib module: ---

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib:

  * This function is missing on all non-glibc platforms: glibc 2.38, macOS 14, FreeBSD 14.0, NetBSD 10.0, OpenBSD 7.5, Minix 3.3.0, AIX 7.3.1, HP-UX 11.31, Solaris 11.4, Cygwin 3.5.3, mingw, MSVC 14, Android.