Use LoopRotate PrepareForLTO stage in NPM

The PrepareForLTO stage of LoopRotate tries to avoid unrolling loops
with calls that might be inlined later.  See D94232 where this was
introduced.

We didn't catch all occurances of the LoopRotatePass in the New Pass
Manager, so the original regression in astar returned with the pass
manager switch.

GitOrigin-RevId: 93d9a4c95aff62bad9603029ee38faedfee40dea
1 file changed