[clang-format][NFC] Rename variable so no shadowing happens

In the loop there is also a Node.

Differential Revision: https://reviews.llvm.org/D115063

clang/lib/Format/UnwrappedLineFormatter.cpp

@@ -1015,9 +1015,9 @@ private:
     QueueType Queue;
 
     // Insert start element into queue.
-    StateNode *Node =
+    StateNode *RootNode =
         new (Allocator.Allocate()) StateNode(InitialState, false, nullptr);
-    Queue.push(QueueItem(OrderedPenalty(0, Count), Node));
+    Queue.push(QueueItem(OrderedPenalty(0, Count), RootNode));
     ++Count;
 
     unsigned Penalty = 0;