说明：  多线程端口扫描程序 实现一个多线程端口扫描程序，满足要求： 1)能同时扫描5个IP地址 2)针对每个IP地址，开设100个线程对其进行扫描 3)如果端口打开，使用函数getservbyport获取服务名，在屏幕上打印：IP port servername,如果是未知的服务，则在屏幕上显示：IP port unkown.
(Multi-threaded port scanner to achieve a multi-threaded port scanner to meet the requirements: 1) can be scanned simultaneously, 5 IP addresses 2) for each IP address, to open 100 threads to scan their 3) If the port open, use the function getservbyport Get service name on the screen printing: IP port servername, if the service is unknown, then displayed on the screen: IP port unkown.)