alpha bootstrap failure wrt loop

[Joern Rennecke]

> This bit?
> 
> 	  /* Biv initial value is not a simple move.  If it is the sum of
>              another biv and a constant, check if both bivs are incremented
>              in lockstep. 

Yes, right below this comment, there is:

              && uid_luid[REGNO_LAST_UID (bl->regno)] < INSN_LUID (loop_end)