osutil: cleanups
- use tabs
- eliminate old-style function pointer calls
- eliminate weird scoping
- eliminate assignment-in-iff
- use !foo rather than foo == NULL
% basic
% unknown
*** [alias] unknown: command bargle is unknown
% ambiguous
*** [alias] ambiguous: command s is ambiguous
% recursive
*** [alias] recursive: circular dependency on recursive
adding foo
% with opts
C foo