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.

avoid using an uninitialised variable.

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

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