[patch] Update loops in cfg manipulation functions

[Zdenek Dvorak]

Hello,

> >I did not measure any change on compiling preprocessed gcc sources (we
> >usually do not spend much time in cfg manipulations).
> >
> OK, but now we are doing it almost everywhere.  I don't expect major 
> differences, but would you mind doing some timings?

as I said, there was no change in compile time on preprocessed gcc sources;
do you have some other benchmark in mind?

Zdenek