[partitions] Adapt to KPMcore 4.2 changes

src/libcalamares/partition/KPMManager.cpp

@@ -71,9 +71,12 @@ InternalManager::InternalManager()
 
 InternalManager::~InternalManager()
 {
+#if defined( WITH_KPMCORE4API ) && !defined( WITH_KPMCORE42API )
     cDebug() << "Cleaning up KPMCore backend ..";
 
-#if defined( WITH_KPMCORE4API )
+    // From KPMcore 4.0 until KPMcore 4.2 we needed to stop
+    // the helper by hand. KPMcore 4.2 ported to polkit directly,
+    // which doesn't need a helper.
     auto backend_p = CoreBackendManager::self()->backend();
     if ( backend_p )
     {