change response m_body send (currently not in use)

OpenSim/Framework/Servers/HttpServer/OSHttpServer/IHttpResponse.cs

@@ -31,7 +31,7 @@ namespace OSHttpServer
         /// before sending everything to the client. It's the simplest
         /// way to serve documents.
         /// </summary>
-        Stream Body { get; set; }
+        Stream Body { get; }
         byte[] RawBuffer { get; set; }
         int RawBufferStart { get; set; }
         int RawBufferLen { get; set; }