refactoring rc.sysinit

[Bill Nottingham]

Nils Philippsen (nphilipp at redhat.com) said: 
> In the past, I found myself in some situations where I would have loved
> to do things before or after a certain stage in rc.sysinit. How things
> were, I had to change the file itself which either made me retrofit
> these changes to a new rc.sysinit or lead to surprises when updating
> initscripts.

Got example usage cases? I'm just skeptical of making things more
complicated and slower if the only usage cases are theoretical.

Bill