to run the standard tests with "--force" (default, can be switched off).


Build-tools/Do-compile:
  1) For an automated log analysis, we need a clear marker in the build log
     whether compile + link succeeded: Write it after successful "make".
  2) Ensure the standard tests are run with "--force" in the default case,
     but allow the old behaviour by an option "--one-error".
  3) Correct a typing error in the usage message.