The mq_close() function shall remove the association between the message
queue descriptor, mqdes, and its message queue. The results of using
this message queue descriptor after successful return from this
mq_close(), and until the return of this message queue descriptor from
a subsequent mq_open(), are undefined.
If the process has successfully attached a notification request to the message
queue via this mqdes, this attachment shall be removed, and the message
queue is available for another process to attach for notification.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html