Clear more stale tail set optimistic types.
ir1opt: Improve CONVERGED-VAR-TYPE precision.
constraint: Refactor some arithmetic relational constraint logic.
loop: Flesh out support for strange loops
Don't have special logic for local calls in DFO and block joining.
find-dominators: Clear stale dominators before recomputing them.
ir1opt: Keep optimistic tail set types updated properly.
Make it easier to call check-ir1-consistency and clear ir1 info more.