Eliminate dead code

Author: cowtowncoder

cbor/src/main/java/com/fasterxml/jackson/dataformat/cbor/CBORParser.java

@@ -376,7 +376,7 @@ public boolean empty() {
             return _stringRefs.empty();
         }
 
-        private Stack<StringRefList> _stringRefs = _stringRefs = new Stack<>();
+        private Stack<StringRefList> _stringRefs = new Stack<>();
         private int _nestedDepth = 0;
     }