Revert D89381 "[SCEV] Recommit "Use nw flag and symbolic iteration count to...

Revert D89381 "[SCEV] Recommit "Use nw flag and symbolic iteration count to sharpen ranges of AddRecs", attempt 2"

This reverts commit a10a64e7.

It broke polly/test/ScopInfo/NonAffine/non-affine-loop-condition-dependent-access_3.ll
The difference suggests that this may be a serious issue.