ResultReporter: fix uninitialized int member

Fixes Axivion(SV70842): Qt-Generic-InitializeAllFieldsInConstructor

Task-number: QTBUG-122619
Pick-to: 6.5
Change-Id: I8ee378246df4767122ca91d65170cae82232044b
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit cf420dc98e45123ff305c1a74b060909fac2d2e6)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/concurrent/qtconcurrentiteratekernel.h

@@ -85,7 +85,7 @@ public:
         return vector.data();
     }
 
-    int currentResultCount;
+    int currentResultCount = 0;
     ThreadEngine<T> *threadEngine;
     QList<T> vector;