XcursorImageLoadCursor: return failure if _XcursorGetDisplayInfo fails

Error: Null pointer dereference (CWE 476)
   Read from null pointer 'info'
        at line 615 of src/cursor.c in function 'XcursorImageLoadCursor'.
          Function '_XcursorGetDisplayInfo' may return constant 'NULL' at line 134, called at line 597.
          Null pointer introduced at line 134 of src/display.c in function '_XcursorGetDisplayInfo'.

[ This bug was found by the Parfait 0.3.7 bug checking tool.
  For more information see http://labs.oracle.com/projects/parfait/

 ]

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>