configs: correctly terminate loop
    
    The switch_to_toplevel() function in process_configs.sh contains a buggy
    loop. It tests whether $path is empty but should test whether $path
    equals "/". (It repeatedly calls dirname on pwd's output, and since pwd
    will return an absolute path this will, eventually, return "/" forever.)
    So let's test for "/" here.
    
    Signed-off-by: Paul Bolle <pebolle@tiscali.nl>