Rename ch3_socket_sample to ch2_socket_sample

Guo Wenxue

2018-11-07 db256c480fa418e23a01836116cb1e0b26c6cbe4

 ch1_fileIO/syserr.c

@@ -1,6 +1,7 @@

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>