dix: added isMPdev field to _DeviceIntRec, is used in GetPointerEvents()

mieq:   avoid merging events from different devices in mieqEnqueue()

xfree86/common
        isMPdev field used from xf86ActivateDevice(), xf86PostMotionEvent()
        and xf86PostButtonEvent()

include/inputstr.h

@@ -288,6 +288,9 @@ typedef struct _DeviceIntRec {
     Bool	inited;			/* TRUE if INIT returns Success */
     Bool        enabled;                /* TRUE if ON returns Success */
     Bool        coreEvents;             /* TRUE if device also sends core */
+#ifdef MPX
+    Bool        isMPDev;                /* TRUE if multipointer device */
+#endif
     GrabPtr	grab;			/* the grabber - used by DIX */
     struct {
 	Bool		frozen;