Operate in stoolie mode when called as libtoolize
    
    When linking `libtoolize` to `slibtoolize` (which is what most distributions that use `slibtool` are doing) it gets run as `slibtool` instead of `slibtoolize` (which is not the expected behavior).

    

    This should allow `slibtool` to operate in `slibtoolize` (or `stoolie` mode) when being called as `libtoolize`.