We want to avoid unsigned integers for reference counting since they
would hide underflows.

Seeing a test failure on vtest I think there might be a race here that I
hope to make more explicit next time it occurs.

A nice and tidy single token to integrate with the parameters table.

Refs #3250

This reverts commit 5367be3f.

polish differently and more sensibly

constify and avoid (char *) = strchr((const char *), x)

error:

vtc_varnish.c  559  Error 158: Assignment to variable 'la' (line 548)
increases capability

as copies of the respective client side flags

When a parameter set is associated at the director level, it should be
in effect with resolve=NOW as with resolve=LAZY.

This adds VTCP_Assert() on the result of read and write calls that deals
with TCP sockets.

When used to check the result of read() and write() calls, it is useful
that a positive return value is accepted in VTCP_Check().

Now that VTCP_Assert() accepts EAGAIN as a legal errno value for read()
errors, uncomment this check.

Since the input value is sometimes the result of a read()/write() call,
avoid truncating the ssize_t value on calling it.

When a socket timeout is set on a socket and the timeout expires, read()
and write() calls on that socket will return (-1) with errno set to
EAGAIN/EWOULDBLOCK.

Consistently use VTCP_Assert when asserting on the result of VTCP_Check().

for VCL_* functions from cache_varnishd.h

Ref: 1e09f422

I find ":path: /foo" more descriptive than "/foo", even though I could
infer which one it was...

Long story short: newer coreutils use `statx` which isn't supported by
old kernel, so the `debian:bullseye` images blew up.

Similarly to Timestamp:Fetch, it is otherwise not possible to distinguish
between time spent in VCL and time spent strictly fetching the response
body.

If significant time is passed in vcl_backend_fetch it becomes difficult
to interpret Timestamp:Connected, which this new timestamp remedies.

Depending on the settings, a timeout can be ambiguous. It's also
generally useful to be able to tell how long it takes, monitor it
and possibly notice a degradation before errors start manifesting
themselves.

it is too far down the stack.  Instead pass the objcore through
the priv structure from ved_deliver() which has legitimate access.

complement the existing c88 test with changing the path of a backend.

They are taking too long, needlessly holding onto job slots forever.

Align with CircleCI for now, even though we could probably do more.