unistd.h
========

POSIX specification:
 http://www.opengroup.org/onlinepubs/9699919799/basedefs/unistd.h.html

Gnulib module: unistd

Portability problems fixed by Gnulib:

  * This header file is missing on some platforms: msvc.

  * The SEEK_* macros are not defined in this file on some platforms: mingw.

  * The *_FILENO macros are not defined in this file on some platforms: OS/2 EMX, mingw.

  * The _exit function is not declared in this file on some platforms: mingw.

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

Portability problems not fixed by Gnulib: