[Fix][Unix] 64-bit issue in ioSetCursorARGB()

 
Hi Ian,

someone found a bug using big cursors on a 64 bit system. I naively  
neglected to use pointerForOop() when casting an oop to a pointer ...

In platforms/unix/vm-display-X11/sqUnixX11.c replace
        (char *)cursorBitsIndex
with
        (char *)pointerForOop(cursorBitsIndex)
That trivial fix is in the olpc branch, and confirmed working:
        http://dev.sugarlabs.org/ticket/380#comment:3

Please add to the trunk :)

- Bert -