Refactor Xsun input device handling to remove SIGIO based event processing.

The keyboard and pointer input events are now processed directly
using fd event notifications registered via DIX SetNotifyFd(),
instead of the legacy SIGIO-based asynchronous I/O.

This refactoring improves the maintainability and portability of
the code by aligning with modern Xorg server practices.

Tested on Sun 3/60 with bwtwo, Type-4 keyboard and mouse.

Merge AbortDDX() into ddxGiveUp() as other upstream DDX servers.

https://gitlab.freedesktop.org/xorg/xserver/-/commit/a23eba2a91024d27da45e5aee1f4215f7ec2ae82
> These are so close to identical that most DDXes implement one in terms
> of the other. All the relevant cases can be distinguished by the error
> code, so merge the functions together to make things simpler.

couple of changes needed for xorg-server 21.1.4.

- AbortDDX() is removed, make it static to avoid code churn since
it is used by internal code now
- LegalModifier() is gone
- if the PRESENT extension isn't included, don't enable the
-fakescreenfps option since it require PRESENT.

fixes builds for sun3 and x68k.

Handle restoring keyboard state via AbortDevices() rather than AbortDDX().

Tested on 3/60. Note AbortDevices() and DEVICE_ABORT in deviceProc
functions were introduced after Xorg 1.14.0:
https://gitlab.freedesktop.org/xorg/xserver/-/commit/9f79e93b6b3416055d08a0e8f9f16d5fd0649e36

add dummy ddxInputThreadInit() if INPUTTHREAD is defined.
fixes sun3 build and should fix x68k build too.

Avoid dumb DevicePtr casts.

Remove more redundant command option arg checks.

Remove redundant command option arg checks.

Call LogInit() for logging to /var/log/Xsun.%s.log as Xorg server.

Import WIP Xorg-Server-1.20'fied monolithic Xsun servers.

This is based on 1.10 version imported into xorg-server.old and
all upstream API changes between xorg-server 1.10 and 1.20 are
applied almost mechanically.
https://github.com/tsutsui/xorg-server-Xsun/commits/xorg-server-1.20

Xsun and XsunMono servers are also confirmed working with bwtwo on
3/60 and tme, and cgtwo on tme. XKB stuff is still to be resolved.