Replace usage of SpinWait struct with simple increment operation. ...

Replace usage of SpinWait struct with simple increment operation.  SpinWait.SpinOnce() takes too much time than the original Thread.SpinWait(5).

BasicTest/Program.cs

@@ -35,15 +35,15 @@ static void MassiveBulkOpsAsync(int AsyncOpsQty, bool preserveOrder, bool withCo
                 var conn = muxer.GetDatabase();
                 muxer.Wait(conn.PingAsync());
 
+                int number = 0;
                 Action<Task> nonTrivial = delegate
                 {
 #if !DNXCORE50
                     Thread.SpinWait(5);
 #else
-                    var spinWait = new SpinWait();
-                    for (int i = 0; i < 5; i++)
+                    for (int i = 0; i < 50; i++)
                     {
-                        spinWait.SpinOnce();
+                        number++;
                     }
 #endif
                 };

StackExchange.Redis.Tests/BasicOps.cs

@@ -234,15 +234,15 @@ public void MassiveBulkOpsAsync(bool preserveOrder, bool withContinuation)
                 var conn = muxer.GetDatabase();
                 muxer.Wait(conn.PingAsync());
 
+                int number = 0;
                 Action<Task> nonTrivial = delegate
                 {
 #if !DNXCORE50
                     Thread.SpinWait(5);
 #else
-                    var spinWait = new SpinWait();
-                    for (int i = 0; i < 5; i++)
+                    for (int i = 0; i < 50; i++)
                     {
-                        spinWait.SpinOnce();
+                        number++;
                     }
 #endif
                 };