xinput: new enum for device_id in some events

xinput: new enum for device_id in some events

add new enum "MoreEventsMask" to be used
by event DeviceKeyPress and derived ones
for field "device_id".

V2: patch revised according to suggestion from Peter Harris:
* remove DeviceBits = 0x7f from the enum in order to avoid
  mixing bit and value in the same enum.
  ( We'd need a way to specify a range of bits for that ... )

spec and code:
http://cgit.freedesktop.org/xorg/lib/libXi/tree/specs/encoding.xml#n1999
http://cgit.freedesktop.org/xorg/proto/inputproto/tree/XIproto.h#n67
http://cgit.freedesktop.org/xorg/lib/libXi/tree/src/XExtInt.c#n534
http://cgit.freedesktop.org/xorg/xserver/tree/dix/eventconvert.c#n348
http://cgit.freedesktop.org/xorg/xserver/tree/Xi/exevents.c#n188

note:
this mask is missing in the following spec:
http://cgit.freedesktop.org/xorg/proto/inputproto/tree/specs/XIproto.txt#n2257