third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/csharp/src/Google.Protobuf/ByteString.cs

 #region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
@@ skipping 285 matching lines @@
         /// <summary>
         /// Returns a hash code for this object. Two equal byte strings
         /// will return the same hash code.
         /// </summary>
         /// <returns>A hash code for this object.</returns>
         public override int GetHashCode()
         {
             int ret = 23;
             foreach (byte b in bytes)
             {
-                ret = (ret << 8) | b;
+                ret = (ret * 31) + b;
             }
             return ret;
         }
 
         /// <summary>
         /// Compares this byte string with another.
         /// </summary>
         /// <param name="other">The <see cref="ByteString"/> to compare this with.</param>
         /// <returns><c>true</c> if <paramref name="other"/> refers to an equal byte string; <c>false</c> otherwise.</returns>
         public bool Equals(ByteString other)
@@ skipping 19 matching lines @@
 
         /// <summary>
         /// Writes the entire byte array to the provided stream
         /// </summary>
         public void WriteTo(Stream outputStream)
         {
             outputStream.Write(bytes, 0, bytes.Length);
         }
     }
 }