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
Portability issues: "msgrcv" in perlport.