update client and socket.c, add DNS support

GuoWenxue

2022-04-19 ea435789dc2fab30ec16fa765a0b6577fe08166a

 apue/2.Socket/socket_client.c

@@ -109,7 +109,8 @@
          }
       }

       //printf("Read %d bytes data from server: '%s'\n", rv, buf);

       sleep(5);
    }