unsetenv
========

POSIX specification: http://www.opengroup.org/susv3xsh/unsetenv.html

Gnulib module: setenv

Portability problems fixed by Gnulib:

  * This function is missing on some platforms: AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 9, mingw, BeOS.

Portability problems not fixed by Gnulib:

  * This function has the return type void instead of int on some platforms.