It makes sense to default to setting Connection: close for vcl_pipe.
Do this before calling vcl_pipe so it's overrideable.

Fixes #1455

Remove adding of X-Forwarded-For from builtin.vcl and put it into the
C code that runs before vcl_recv.  This makes it more likely that it's
properly set when the user VCL runs.

Fixes: #1454

Mostly an attempt at pointing people that send pull requests on Github
in the right direction.

Move showing of debug counters from 'h' key to 'd' inside a running
varnishstat.

Fixes	#1449

Make sure we do not send a regular "end-chunk" to the
client if the streaming fetch fails.

to reduce code duplication a little bit.

on IMS fetch.

This should possibly be an official VSL record ?

This will be revisited post 4.0. Reorder while I'm here.

Only varnishreplay is left now.

This matches the rest of the code.