render: set anim cursor state for pointer enabled devices only

The structure containing the state of animated cursor was amended within
SpriteInfoRec, removing all previously privates logic to keep such state.

API change: It was removed MAXDEVICES dependency \o/

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

include/inputstr.h

@@ -477,6 +477,14 @@ typedef struct _SpriteInfoRec {
     DeviceIntPtr        paired;      /* The paired device. Keyboard if
                                         spriteOwner is TRUE, otherwise the
                                         pointer that owns the sprite. */ 
+
+    /* keep states for animated cursor */
+    struct {
+        CursorPtr       pCursor;
+        ScreenPtr       pScreen;
+        int             elt;
+        CARD32          time;
+    } anim;
 } SpriteInfoRec, *SpriteInfoPtr;
 
 /* device types */