Receives bytes on a socket and places them into scattered
    buffers.
    Format
      #include  <types.h>
      #include  <socket.h>
      int recvmsg  ( int s, struct msghdr msg, int flags ); (BSD
                   Version 4.4)
      int recvmsg  ( int s, struct omsghdr msg, int flags ); (BSD
                   Version 4.3)