From: Chris Wright <chrisw@osdl.org>

SUSv3 doesn't seem to specify one way or the other.  I don't have the POSIX
specs, and the old docs I have suggest that mq_open() creates an object
which is to be closed upon exec.

Jakub said:

  I think it is valid and required:

    http://www.opengroup.org/onlinepubs/007904975/functions/exec.html

    All open message queue descriptors in the calling process shall be
    closed, as described in mq_close()

  I'll add a new test for this into glibc testsuite.