Changes:
* If only one bootable device is available, boot from it.
* Silence PDC warnings with HP-UX 11.11
* Inform Linux about fw_cfg port addresses
* Make power switch button configurable from qemu
* Clear screen on machine reset
* Add fw_cfg option to enable runtime debug info
* Fix panic on OpenBSD/6.7 regarding STI console
* Set text planes and used_bits in STI fields
* Fix mon_tbl entries
* Convert sti_region_list to an initialized struct

Signed-off-by: Helge Deller <deller@gmx.de>