Added ability to generate last-value of linear induction.

Also added utility to update fetches in induction nodes.

Rationale:
This is a first step towards the larger CL that introduces
a new loop optimization framework in the optimizing compiler
(see https://android-review.googlesource.com/#/c/271392/3).

Change-Id: Ibecd674c8146d9665340e68718c498555646129a
Tests: induction_var_range_test