Basic block renumbering removal

[Zdenek Dvorak]

Hello.

> Since I don't want to read through a patch of this size again,
> and none of the points above is critical to correctness, I've
> committed the patch as-is.

Sorry; I haven't tried to compile objc. I've seen the problem before (iterative
dataflow does not have to terminate for some initial solutions, but without my
patch gcc somehow (not quite sure how) avoids them), but I hoped I fixed it
already).  I will try to fix it asap, but it might be better to revert the
patch for now.

Zdenek