Induction variable range analysis.

Rationale: by computing an upper bound on the trip count of each
           loop after induction var analysis has completed, a
	   simple range analysis yields lower and upper bounds on
	   all induced expressions in a loop; this analysis
	   plugs directly into BCE (follow-up CL).

Change-Id: I46a3fe48721ca372547199b39a3498c47992597d