fix various errors and warnings with xorg-server 1.20:

- no Error() in scope
- more wakeup/blockhandler ABI changes
- more notify fd API changes
- more xf86CursorResetCursor changes
- lots of char* -> const char*
- fix ati kms config.h now HAVE_XF86_CURSOR_RESET_CURSOR is available
- another xf86GetOS() is removed fix
- OsBlockSIGIO() etc, -> old, but still around API until properly converted
- don't free const char * data owned by some other system

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

un-merge the new ati driver from the old location.

initial import of xf86-video-ati-7.8.0

initial import of xf86-video-ati-6.14.6.

NetBSD note: The libdrm requirement seems to be KMS related which we do
not have.

* 6.15.6
This version requires the latest libdrm 2.4.36 release, and fixes a few
other bugs seen since 6.14.5.
* 6.14.5
- add solid picture accel
- tiling fixes
- new pci ids
- 6xx-9xx Xv improvements
- support for upcoming xserver API changes
- bug fixes