Lucene.Net.Util.Automaton.DacuikMihovAutomatonBuilder: Reduce the num…

…ber of zero length array allocations (#295, #261)

src/Lucene.Net/Util/Automaton/DaciukMihovAutomatonBuilder.cs

@@ -42,11 +42,20 @@ public sealed class State // LUCENENET NOTE: Made public because it is returned
         {
             /// <summary>
             /// An empty set of labels. </summary>
-            private static readonly int[] NO_LABELS = new int[0];
-
+            private static readonly int[] NO_LABELS =
+#if FEATURE_ARRAYEMPTY
+                Array.Empty<int>();
+#else
+                new int[0];
+#endif
             /// <summary>
             /// An empty set of states. </summary>
-            private static readonly State[] NO_STATES = new State[0];
+            private static readonly State[] NO_STATES =
+#if FEATURE_ARRAYEMPTY
+                Array.Empty<State>();
+#else
+                new State[0];
+#endif
 
             /// <summary>
             /// Labels of outgoing transitions. Indexed identically to <see cref="states"/>.