logging: don't close stderr in finalization

When logging to stderr, don't close it in finalization in case something
else still wanted to write to it. Leave it as it is together with stdin
and stdout.

logging.c

@@ -91,7 +91,7 @@ LOG_Finalise(void)
   if (system_log)
     closelog();
 
-  if (file_log)
+  if (file_log && file_log != stderr)
     fclose(file_log);
   file_log = NULL;
   Free(file_log_path);