根据哲学家进程间的相互制约关系，设置合理的信号量及信号量初值。
创建5个线程，分别模拟5个哲学家进程。
在哲学家线程之间通过对信号量的P,V操作，实现线程之间的同步关系。(According to the mutual restriction between the philosophers' process, the reasonable signal quantity and the initial value of the signal quantity are set up.
Create 5 threads to simulate the 5 philosopher processes, respectively.
The synchronization relationship between threads is realized between the philosophers' threads through the P and V operations of the semaphore.)