Improvements in induction range analysis.

Rationale:
Uses range analysis while determining whether trip-counts
are "safe", which improves analysis of triangular loops.
Also implements more effective triangular loop analysis
by evaluating induction information only once and using
a top level hint (instead of the "iterative refinement"
that was used earlier). Also fixes analysis of triangular
trip counts that may wrap-around. All with tests.

Test: see induction_var_range_test/530-checker-loops*

BUG=27151190

Change-Id: I1877c8ce0c9a52005900eb9dfdbb1918df100278