mieq: avoid merging events from different devices in mieqEnqueue()
xfree86/common
isMPdev field used from xf86ActivateDevice(), xf86PostMotionEvent()
and xf86PostButtonEvent()
merge with code cleanup from master
GetPointerEvents treats events in the same way as XINPUT devices when flag
has POINTER_MULTIPOINTER set.
xfree86/common:
added XI86_MP_DEVICE flag and parsing in xf86ProcessCommonOptions
added POINTER_MULTIPOINTER define. Is used in xf86PostMotionEvent and
xf86PostButtonEvent for the flags that are passed into GetPointerEvents()
global:
added flags to configure.ac to enable/disable MPX define
added flags to dix-config.h.in to define MPX