stdlib.h
========

POSIX specification:
 https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdlib.h.html

Gnulib module: stdlib, system-posix

Portability problems fixed by the Gnulib module stdlib:

  * The macros EXIT_SUCCESS and EXIT_FAILURE are not defined on some platforms.

  * Some platforms provide a NULL macro that cannot be used in arbitrary expressions: NetBSD 5.0

Portability problems fixed by the Gnulib module system-posix:

  * The macros WIFSIGNALED, WIFEXITED, WIFSTOPPED, WTERMSIG, WEXITSTATUS, WNOHANG, WUNTRACED, WSTOPSIG are not defined in this header file (only in <sys/wait.h>) on some platforms: MirBSD 10.

Portability problems not fixed by Gnulib:

  * System status macros such as WEXITSTATUS require an lvalue argument on some platforms. macOS 11.1.