The patch adds the following changes:
1. Introduce cmake option WITH_SYSTEMD.
2. Introduce server command-line option --daemonize to run server
   in daemon mode.
3. Introduce exit code macros MYSQLD_SUCCESS_EXIT, MYSQLD_ABORT_EXIT
    and MYSQLD_FAILURE_EXIT and it's related changes.
4. Auto generate mysqld.service based on install configuration
5. Install related cmake changes.