C#: Disable the write-through of the logger, as this is a theoretical slowdown, and results in less readable log files when multiple extractors are running concurrently.

csharp/extractor/Semmle.Util/Logger.cs

@@ -72,7 +72,6 @@ namespace Semmle.Util.Logging
                     Directory.CreateDirectory(dir);
                 writer = new PidStreamWriter(new FileStream(outputFile, FileMode.Append, FileAccess.Write,
                     FileShare.ReadWrite, 8192));
-                writer.AutoFlush = true;
             }
             catch (Exception ex)  // lgtm[cs/catch-of-all-exceptions]
             {