* module/language/cps/utils.scm (solve-flow-equations): Revert to take
separate in and out maps. Take an optional initial worklist.
* module/language/cps/slot-allocation.scm: Adapt to solve-flow-equations
change.
* module/language/cps/slot-allocation.scm (compute-lazy-vars):
(compute-live-variables): Adapt to solve-flow-equations interface
change.
* module/language/cps/utils.scm (solve-flow-equations): Move here. Use
an init value instead of an init map.