dix: send the current axis value in DeviceChangedEvents (#62321)

X.Org Bug 62321 <http://bugs.freedesktop.org/show_bug.cgi?id=62321>

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Keith Packard <keithp@keithp.com>

include/eventstr.h

@@ -175,6 +175,7 @@ struct _DeviceChangedEvent {
     struct {
         uint32_t min;           /**< Minimum value */
         uint32_t max;           /**< Maximum value */
+        double value;           /**< Current value */;
         /* FIXME: frac parts of min/max */
         uint32_t resolution;    /**< Resolution counts/m */
         uint8_t mode;           /**< Relative or Absolute */