move unistd include from cpp to h

src/comm.cpp

 #include <string.h>
-#include <unistd.h>
 #include <sys/select.h>
 #include <sys/ioctl.h>
 #include "comm.h"

src/comm.h

 #ifndef _COMM_H
 #define _COMM_H
 
+#include <unistd.h>
 #include <list>
 #include "eventserver.h"
 #include "threadserver.h"