Fix profile updating after complette loop unrolling

[Zdenek Dvorak]

Hello,

> other common source of weird profiles is complette loop unrolling.  At the
> moemnt updating is done via generic loop peeling mechanizm, that expect that
> last copy of loop to still loop at the average same number of times as did the
> original loop causing the other more frequent copies relatively cold
> causing some relatively minnor regressions in gzip.
> 
> This patch don't get the updating 100% right either whent the loop has nonzero
> probability of exiting by other edges too, but I quite convinced myself that
> there is no way to do much saner job (ie one might try to guess how histogram
> of number of iterations of the loop but without that it is not quite possibly
> to get counts of loop exit edges right)
> 
> Zdenek, does this code seems to make sense to you?

seems OK to me.

Zdenek