[krbdev.mit.edu #8671] minor bug in ksu

[Greg Hudson via RT]

If argc is 0, ksu should crash with a null dereference at line 144 
where it does strlen() on argv[0].  I believe that happens with every 
program in the MIT krb5 tree, but we have received reports of argc == 0 
issues specifically for ksu twice this month, which seems odd.  Out of 
curiosity, can you explain how you arrived at this issue?