Adds support for the new TouchClass for multitouch-capable servers/devices.

New events:
  XITouchOwnershipEvent

New event types handled:
  XITouchBegin, XITouchUpdate, XITouchEnd
  XIRawTouchBegin, XIRawTouchUpdate, XIRawTouchEnd

New functions:
  XIGrabTouchBegin ... passive grabs on touches
  XIUngrabTouchBegin
  XIAllowTouchEvents ... Allow/reject touch event sequences

New XIQueryDevice classes:
  XITouchClassInfo

Requires libX11 1.5 for GetReqSized

Co-authored by: Chase Douglas <chase.douglas@canonical.com>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>