This function exists only on Linux, FreeBSD, and illumos and is therefore
missing on many non-glibc platforms:
glibc 2.6, macOS 11.1, FreeBSD 12.0, NetBSD 9.0, OpenBSD 6.7, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, Solaris 11.4, Cygwin 2.9, mingw, MSVC 14.