Fix casting to uint64_t when returning unix system time

drivers/unix/os_unix.cpp

@@ -187,7 +187,7 @@ uint64_t OS_Unix::get_system_time_secs() const {
 uint64_t OS_Unix::get_system_time_msecs() const {
 	struct timeval tv_now;
 	gettimeofday(&tv_now, NULL);
-	return uint64_t(tv_now.tv_sec * 1000 + tv_now.tv_usec / 1000);
+	return uint64_t(tv_now.tv_sec) * 1000 + uint64_t(tv_now.tv_usec) / 1000;
 }
 
 OS::Date OS_Unix::get_date(bool utc) const {