Fix launchIndex in the presence of ExtraRun and in-process SeparateLogic diagnosers.

Author: timcassell

src/BenchmarkDotNet/Running/BenchmarkRunnerClean.cs

@@ -568,7 +568,7 @@ private static (bool success, List<ExecuteResult> executeResults, List<Metric> m
                     resolver,
                     extraRunCompositeDiagnoser,
                     compositeInProcessDiagnoser,
-                    launchCount + 1,
+                    ++launchCount,
                     Diagnosers.RunMode.ExtraRun);
 
                 if (executeResult.IsSuccess)
@@ -597,7 +597,7 @@ private static (bool success, List<ExecuteResult> executeResults, List<Metric> m
                         resolver,
                         separateLogicCompositeDiagnoser,
                         compositeInProcessDiagnoser,
-                        launchCount + 1,
+                        ++launchCount,
                         Diagnosers.RunMode.SeparateLogic);
 
                     if (executeResult.IsSuccess)