Backport of this xorg-xserver patch:

  commit 3083c5d0c4386cdd7083b7a83ac72fdad2f1e61e
  Author: Michel Dänzer <daenzer@vmware.com>
  Date:   Mon Mar 22 18:01:17 2010 +0100

    Xext: Fix cursor reference counting hazard.

    Make sure the reference count of the new cursor is increased before the old
    one is decreased, otherwise bad things will happen if they're one and the
    same and the reference count is 1 initially. Not sure this can actually happen
    here, but better safe than sorry.
Signed-off-by: Michel Dänzer <daenzer@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Signed-off-by: Keith Packard <keithp@keithp.com>