QCocoaDrag::maybeDragMultipleItems - fix erroneous size check

Due to somewhat inverted logic introduced by the 8481a9fc97,
testing number of items in a pasteboard happens _before_ we fill it,
which is wrong and useless. As a result, maybeDragMultipleItems will
prevent the single item drag.

Pick-to: 5.15
Task-number: QTCREATORBUG-24665
Task-number: QTBUG-86786
Change-Id: Ia4be9fc56677575bb363cbb8b1adbea59e6c3b0b
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/plugins/platforms/cocoa/qcocoadrag.mm

@@ -186,7 +186,7 @@ bool QCocoaDrag::maybeDragMultipleItems()
     const auto &qtUrls = m_drag->mimeData()->urls();
     NSPasteboard *dragBoard = [NSPasteboard pasteboardWithName:NSPasteboardNameDrag];
 
-    if (int(dragBoard.pasteboardItems.count) == 1 && qtUrls.size() <= 1) {
+    if (qtUrls.size() <= 1) {
         // Good old -dragImage: works perfectly for this ...
         return false;
     }