Makefile change to restart bootstraps

[Richard Earnshaw]

>     The new `make bootstrap' continues from the point where it was
>     interrupted.  The main advantage is that it's restartable.  
> 
> This is the point: I don't see *any* case where that commonly needed. All
> the cases you mention are where it would be a *bad idea* to restart it that
> way since the previous files won't be recompiled with the changed compiler:
> this is a recipe to having undetected problems.
> 
> Besides, it's always been possible to restart a bootstrap in the middle if
> you wanted to: that's what "make bootstrap2" and "make bootstrap3" are for.

I strongly agree.  The new system relies *far* too heavily on stamp files 
which are completely non-intuitive, since they bear no relation to what is 
happening.  stage_[abcde] means nothing to me.

R.