msgrcv ID,VAR,SIZE,TYPE,FLAGS
            Calls the System V IPC function msgrcv to receive a message from
            message queue ID into variable VAR with a maximum message size
            of SIZE. Note that when a message is received, the message type
            as a native long integer will be the first thing in VAR,
            followed by the actual message. This packing may be opened with
            "unpack("l! a*")". Taints the variable. Returns true if
            successful, false on error. See also "SysV IPC" in perlipc and
            the documentation for "IPC::SysV" and "IPC::SysV::Msg".

            Portability issues: "msgrcv" in perlport.