Codegen: stats and progress issues (#14763)

The `--stats` and `--progress` params had a couple issues:

- codegen progress isn't updated when `--threads=1` (always the case on Windows);
- only stats need to collect reused modules (progress doesn't).

Author: ysbaddaden

src/compiler/crystal/compiler.cr

@@ -505,8 +505,6 @@ module Crystal
     private def codegen_many_units(program, units, target_triple)
       all_reused = [] of String
 
-      wants_stats_or_progress = @progress_tracker.stats? || @progress_tracker.progress?
-
       # Don't start more processes than compilation units
       n_threads = @n_threads.clamp(1..units.size)
 
@@ -516,7 +514,12 @@ module Crystal
       if n_threads == 1
         units.each do |unit|
           unit.compile
-          all_reused << unit.name if wants_stats_or_progress && unit.reused_previous_compilation?
+          @progress_tracker.stage_progress += 1
+        end
+        if @progress_tracker.stats?
+          units.each do |unit|
+            all_reused << unit.name && unit.reused_previous_compilation?
+          end
         end
         return all_reused
       end
@@ -597,10 +600,10 @@ module Crystal
             exit 1
           end
 
-          if wants_stats_or_progress
+          if @progress_tracker.stats?
             all_reused << result["name"].as_s if result["reused"].as_bool
-            @progress_tracker.stage_progress += 1
           end
+          @progress_tracker.stage_progress += 1
         end
 
         all_reused