dix: reference the cursor just once in InitializeSprite()

The new current cursor was being referenced twice, resulting in a
memory leak when the current server generation ended.

Signed-off-by: Frank Binns <frank.binns@imgtec.com>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

dix/events.c

@@ -3237,7 +3237,7 @@ InitializeSprite(DeviceIntPtr pDev, WindowPtr pWin)
     pCursor = RefCursor(pCursor);
     if (pSprite->current)
         FreeCursor(pSprite->current, None);
-    pSprite->current = RefCursor(pCursor);
+    pSprite->current = pCursor;
 
     if (pScreen) {
         (*pScreen->RealizeCursor) (pDev, pScreen, pSprite->current);