various updates to build against xorg-server 21.1.3.

- avoid a const issue with an expanded __UNCONST().
- cope with renamed member names
- deal with "xf86RamDac.h" going away (now use "xf86Cursor.h")

fix merge botches.

re-add files autoconf files that the build sort of needs at
least configure for. command used:

% cd /usr/xsrc/external/mit/xf86-video-intel/dist
% autoreconf -I m4 -I /usr/xsrc/external/mit/xorg-server/dist -i

tested on sandy bridge and kaby lake.

merge xf86-video-intel 6afed33b2d673d88674f0c76efe500ae414e8e1b.

make the intel driver work again with xorg-server 1.20:

- BlockHandler() timeout value changed from struct timeval ** to int **
that has a millisecond value.

- avoid a NULL ptr deref in ProcXF86BigfontQueryFont() and make some
code actually able to be run.

mostly fix amd64 xorg-server 1.20 builds:

- avoid bswap_16 etc defines for now. ends up with code-in-decl
- more ABI_VERSION 23 fixes (BlockHandler/WakeHandler) including re-fix
from previous
- more Notify API
- more shadowUpdatePackedWeak() removal
- remove fd_set handling from intel driver (part of ABI_VERSION 23)
- cope better with PixMap/Drawable separation in new server
- remove support for maxHValue and maxVValue (XXX?)
- hide drmmode_udev_notify() when not building udev
- comment out nouveau 'wfb' support, xorg-server 1.20 only supplies
either 'wfb' or 'fb' interface, not both, and we choose 'fb'
- define 'pointer' in nv_proto.h rather than relying upon Xdefs.h
- normalise the value of _XTYPEDEF_POINTER
- EGL is broken (missing) in xsrc currently

various updates for xorg-server 1.20. some of these are work-in-progress,
the xsrc build is broken for most ports currently.

- xf86DisableRandR() is gone
- use HAVE_NOTIFY_FD like other modern drivers in compat-api.h
- pRotatedPixmap is done
- some PixmanPtr is now DrawablePtr (this one is all over problem with many
consumers, and perhaps the major breakage point currently.)

initial import of xf86-video-intel-2.99.917

Import the latest from x.org; no improvement over the current screen corruption.

initial import of xf86-video-intel-2.21.15