tested and fixed unix os_system_time_msec()

drivers/unix/os_unix.cpp

@@ -225,8 +225,9 @@ uint64_t OS_Unix::get_unix_time() const {
 
 uint64_t OS_Unix::get_system_time_msec() const {
 	struct timeval tv_now;
-	gettimeofday(&tv_now, null);
-	uint64_t msec = tv_now.tv_.sec / 1000;
+	gettimeofday(&tv_now, NULL);
+	localtime(&tv_now.tv_usec);
+	uint64_t msec = tv_now.tv_usec/1000;
 	return msec;
 }