vcl_backend_error changes

[Nils Goroll]

So here's the second suggestion update from the "thoughts about vcl cleanup
around ..." thread:

* add status and reason to abandon which get pre-set for the call to
  vcl_synth


  vcl_backend_fetch {
	return (abandon(901, "coming from vcl_backend_fetch"));
  }
  vcl_backend_response {
	return (abandon(902, "coming from vcl_backend_response"));
  }
  vcl_backend_error {
	return (abandon(903, "coming from vcl_backend_error"));
  }
  vcl_synth {
	# resp.status is now 901, 902 or 903 for the cases above
	# resp.reason is set to "coming from ..."
  }

* add return(error(status, reason)) to fail to vcl_backend_error
  and have status and reason pre-set

  vcl_backend_fetch {
	return (error(901, "coming from vcl_backend_fetch"));
  }
  vcl_backend_response {
	return (error(902, "coming from vcl_backend_response"));
  }
  vcl_backend_error {
	# beresp.status is now 901 or 902 for the cases above
	# beresp.reason is set to "coming from ..."
  }


Nils