Get and set varsets/vartypes in proc_infos together.

compiler/hlds_pred.m:
    We eventually want to replace the varset and vartypes fields in
    each proc_info with a var_table, but it is not practical to do so
    at once; it will have to be done gradually, a few modules at most
    at a time. During this process, we will need a way either

    - to let already converted modules get a var_table out of the proc_info,
      and put an updated var_table back into a proc_info, even though
      proc_infos still contain varset and vartypes fields, or

    - to let not-yet-converted modules get varsets and vartypes out of the
      proc_info, and put updated varsets and vartypes back into a proc_info,
      even though proc_infos already store a var_table.

    The latter cannot be done in two halves (i.e. set the varset half
    of the var_table, and then set its vartypes half), and while the former
    *can* be done that way, it is more efficient to do them at the same time.

    Therefore as a first step, this diff replaces the indiviual getter
    and setter predicates of the varset and vartypes fields of proc_info
    with a getter that gets both and a setter that sets both.

    Put the varset and vartypes next to each other in a structure.

compiler/code_info.m:
    Delete a function that duplicates a function in var_table.m.

    Conform to the change above.

compiler/det_report.m:
    Factor out some common code.

    Conform to the change above.

compiler/det_util.m:
    Delete a no-longer-needed predicate.

    Conform to the change above.

compiler/higher_order.m:
    Fix an old oversight: when deleting variables from the vartypes,
    delete them from the varset as well.

    Conform to the change above.

compiler/liveness.m:
    Avoid constructing and traversing a list unnecessarily.

    Conform to the change above.

compiler/accumulator.m:
compiler/add_heap_ops.m:
compiler/add_trail_ops.m:
compiler/arg_info.m:
compiler/build_mode_constraints.m:
compiler/bytecode_gen.m:
compiler/call_gen.m:
compiler/clause_to_proc.m:
compiler/closure_analysis.m:
compiler/code_gen.m:
compiler/code_loc_dep.m:
compiler/complexity.m:
compiler/continuation_info.m:
compiler/cse_detection.m:
compiler/ctgc.datastruct.m:
compiler/ctgc.util.m:
compiler/deep_profiling.m:
compiler/deforest.m:
compiler/delay_construct.m:
compiler/delay_partial_inst.m:
compiler/dep_par_conj.m:
compiler/det_analysis.m:
compiler/direct_arg_in_out.m:
compiler/disj_gen.m:
compiler/equiv_type_hlds.m:
compiler/exception_analysis.m:
compiler/float_regs.m:
compiler/follow_code.m:
compiler/goal_mode.m:
compiler/goal_path.m:
compiler/hlds_out_pred.m:
compiler/hlds_rtti.m:
compiler/hlds_statistics.m:
compiler/inlining.m:
compiler/intermod.m:
compiler/intermod_analysis.m:
compiler/introduce_exists_casts.m:
compiler/introduce_parallelism.m:
compiler/lambda.m:
compiler/lco.m:
compiler/live_vars.m:
compiler/loop_inv.m:
compiler/mark_tail_calls.m:
compiler/ml_accurate_gc.m:
compiler/ml_args_util.m:
compiler/ml_closure_gen.m:
compiler/ml_gen_info.m:
compiler/ml_proc_gen.m:
compiler/mode_info.m:
compiler/modecheck_goal.m:
compiler/modes.m:
compiler/par_loop_control.m:
compiler/pd_debug.m:
compiler/pd_info.m:
compiler/pd_util.m:
compiler/polymorphism_info.m:
compiler/proc_gen.m:
compiler/purity.m:
compiler/push_goals_together.m:
compiler/quantification.m:
compiler/rbmm.add_rbmm_goal_infos.m:
compiler/rbmm.live_variable_analysis.m:
compiler/rbmm.points_to_graph.m:
compiler/rbmm.points_to_info.m:
compiler/rbmm.region_liveness_info.m:
compiler/rbmm.region_transformation.m:
compiler/recompute_instmap_deltas.m:
compiler/saved_vars.m:
compiler/simplify_goal_unify.m:
compiler/simplify_info.m:
compiler/simplify_proc.m:
compiler/size_prof.m:
compiler/ssdebug.m:
compiler/stack_alloc.m:
compiler/stack_layout.m:
compiler/stack_opt.m:
compiler/stm_expand.m:
compiler/store_alloc.m:
compiler/structure_reuse.analysis.m:
compiler/structure_reuse.direct.choose_reuse.m:
compiler/structure_reuse.direct.detect_garbage.m:
compiler/structure_reuse.indirect.m:
compiler/structure_reuse.lbu.m:
compiler/structure_reuse.lfu.m:
compiler/structure_sharing.analysis.m:
compiler/structure_sharing.domain.m:
compiler/switch_detection.m:
compiler/table_gen.m:
compiler/tabling_analysis.m:
compiler/term_constr_build.m:
compiler/term_constr_initial.m:
compiler/term_errors.m:
compiler/term_pass1.m:
compiler/term_pass2.m:
compiler/trace_gen.m:
compiler/trailing_analysis.m:
compiler/try_expand.m:
compiler/tupling.m:
compiler/unneeded_code.m:
compiler/untupling.m:
compiler/unused_args.m:
compiler/unused_imports.m:
    Conform to the change above.

compiler/code_gen.m

@@ -87,7 +87,7 @@ generate_goal(ContextModel, Goal, Code, !CI, !CLD) :-
     trace [compiletime(flag("codegen_goal")), io(!IO)] (
         some [ModuleInfo, VarSet, GoalDesc] (
             code_info.get_module_info(!.CI, ModuleInfo),
-            proc_info_get_varset(ProcInfo, VarSet),
+            proc_info_get_varset_vartypes(ProcInfo, VarSet, _VarTypes),
             GoalDesc = describe_goal(ModuleInfo, VarSet, Goal),
 
             ( if should_trace_code_gen(!.CI) then
@@ -192,7 +192,7 @@ generate_goal(ContextModel, Goal, Code, !CI, !CLD) :-
     trace [compiletime(flag("codegen_goal")), io(!IO)] (
         some [ModuleInfo, VarSet, GoalDesc] (
             code_info.get_module_info(!.CI, ModuleInfo),
-            proc_info_get_varset(ProcInfo, VarSet),
+            proc_info_get_varset_vartypes(ProcInfo, VarSet, _VarTypes),
             GoalDesc = describe_goal(ModuleInfo, VarSet, Goal),
 
             ( if should_trace_code_gen(!.CI) then