Calls the System V IPC function msgsnd to send the message MSG to the
message queue ID. MSG must begin with the native long integer message
type, be followed by the length of the actual message, and then finally
the message itself. This kind of packing can be achieved with
pack("l! a*", $type, $message)
. Returns true if successful,
false on error. See also the
Portability issues: msgsnd in perlport.