[Bug tree-optimization/115825] Loop unrolling increases code size with -Os

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115825

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
For avr, we get:

size: 5-4, last_iteration: 5-4
  Loop size: 5
  Estimated size after unrolling: 5

So something is under-estimating the size after unrolling.