Add new hover move action and scroll wheel plumbing.

Added support for tracking the mouse position even when the mouse button
is not pressed.  To avoid confusing existing applications, mouse movements
are reported using the new ACTION_HOVER_MOVE action when the mouse button
is not pressed.

Added some more plumbing for the scroll wheel axes.  The values are
reported to Views but they are not yet handled by the framework.

Change-Id: I1706be850d25cf34e5adf880bbed5cc3265cf4b1
diff --git a/native/include/android/input.h b/native/include/android/input.h
index d531489..d516037 100644
--- a/native/include/android/input.h
+++ b/native/include/android/input.h
@@ -281,7 +281,13 @@
     /* A non-primary pointer has gone up.
      * The bits in AMOTION_EVENT_ACTION_POINTER_INDEX_MASK indicate which pointer changed.
      */
-    AMOTION_EVENT_ACTION_POINTER_UP = 6
+    AMOTION_EVENT_ACTION_POINTER_UP = 6,
+
+    /* A change happened but the pointer is not down (unlike AMOTION_EVENT_ACTION_MOVE).
+     * The motion contains the most recent point, as well as any intermediate points since
+     * the last hover move event.
+     */
+    AMOTION_EVENT_ACTION_HOVER_MOVE = 7,
 };
 
 /*