Allow usb tablet to be used with vmware-vga hwcursor.

Assume that in absolute mode the guest cursor always follows host cursor
and there's no need to move host cursor.  This avoids a strange feedback
loop.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6477 c046a42c-6fe2-441c-8c8c-71466251a162
