[FileItemRolesUpdater] Reserve space in two temporary lists

Reserve sufficient space to avoid reallocation later. Overallocating
actually requires less memory than growing and copying it, and it
is freed immediately after anyway.

src/kitemviews/kfileitemmodelrolesupdater.cpp

@@ -954,6 +954,8 @@ void KFileItemModelRolesUpdater::updateChangedItems()
 
     QList<int> visibleChangedIndexes;
     QList<int> invisibleChangedIndexes;
+    visibleChangedIndexes.reserve(m_changedItems.size());
+    invisibleChangedIndexes.reserve(m_changedItems.size());
 
     // Iterate over a const copy because items are deleted within the loop
     const auto changedItems = m_changedItems;