Just like the file cursor reads from stdin when opening "-". And in
addition, teach varnishlog to also write to stdout when it is opening
the file directly. Likewise, put varnishncsa on par with varnishlog in
that regard.

It is now possible to compress binary VSL on the fly without taking
a detour to the file system, see u00019.vtc for an example.

Considering how VUT daemonizes, a "-w -" option in daemon mode becomes
an error as well.

Refs #3740

When vsl_reclen (maximum length of a record) is close to vsl_buffer,
the vsl buffer is flushed to the main shared memory log for every
record. This is because we test if there is space for vsl_reclen, not
the actual size of the formatted log record (which likely is much
smaller).

Fix this by doing the formatting in up to two stages. If the first
stage shows that we overflowed, but would not have overflown
vcl_reclen if there was more room in the buffer, then flush and redo
the formatting. This limits the extra work of formatting twice only to
the one record that happened to overflow the buffer.

Otherwise valid code can panic on workspace exhaustion:

    std.ip(req.http.X-Real-IP, std.ip(req.http.X-Client-IP, client.ip))

If the nested std.ip() call runs out of workspace, it will return a null
ip instead of the fallback, and since the outer std.ip() call is getting
a fallback argument, it will panic upon checking the suckaddr sanity.

Refs a3b26d0b

{req,bereq}.time remain constant across restarts/retries
req_top.time remains constant across esi includes

The other values represent the time when the respective object
was created.

(Last part of #3599)

(4th part of #3599)

(3rd part of #3599)

(2nd part of #3599)

(First part of #3599)

Dont limit ourselves to a set number of VSL records to include
the "0 CLI" we want, various platforms emit a number of Debug
messages relating to sockopt

Use the `process p%d -expect-text` mechanism to wait only as
long as necessary for the "0 CLI"

Dont limit ourselves to a set number of VSL records to include
the "0 CLI" we want, various platforms emit a number of Debug
messages relating to sockopt

Use the `process p%d -expect-text` mechanism to wait only as
long as necessary for the "0 CLI"

Refs #3740

Closes #3692

Conflicts:
	bin/varnishd/cache/cache_acceptor.c

Instead of having a single global check that all acceptors may race
towards, this check now happens on a per listen socket basis. For
sockets with a different inheritance behavior on a single system, we
avoid having the first connection dictate what may be inherited by
a connection socket from its listen socket for all the other listen
addresses.

At least on Linux, Unix-domain sockets DO NOT inherit options like
SO_{RCV,SND}TIMEO even though TCP sockets do. On the off chance that
even sockets of the same family could behave differently, like for
example a regular vs a loopback TCP session, this is done on a per
listen address basis. To avoid cache-acceptor coordination with the
acceptor worker threads of a given listen address, workers will
individually perform this check once and for all when the first
connection is accepted.

We also stay defensive in the event of a parameter change, just in
case a previous test would assume inheritance because the Varnish
parameter value would match the kernel default value. Once a mismatch
is observed for a given connection with a given socket, the inheritance
test is no longer performed needlessly for this combination.

A race still exists between acceptors from different thread pools for
a given listen address, but this race is identical to the previous one
based on the former global need_test variable.

Although the inheritance check leaks into struct listen_sock, it is
opaque so everything can remain contained inside cache_acceptor.c.

Some aspects of this change (including the clarification comments) are
from @mbgrydeland.

Refs #2722

And while at it, update the SO_LINGER explanation to match reality.

Refs 7eba9460

Conflicts:
	bin/varnishd/cache/cache_acceptor.c

The SO_KEEPALIVE justification used to precede such a constant and was
left confusingly lingering over the unrelated need_test variable.

Conflicts:
	bin/varnishd/cache/cache_acceptor.c

Using the tmp sock_arg for storage, we can test all values with the same
logic and only differentiate hard-coded options from parameterized ones.

Stylistic polish by @mbgrydeland.

Conflicts:
	bin/varnishd/cache/cache_acceptor.c

They can be stored directly in the sock_opts array or on the stack.

Conflicts:
	bin/varnishd/cache/cache_acceptor.c

The sess and listen_sock structs contain everything we need to find or
infer the former `sock`, `uds` and `force` arguments. In particular, it
helps distinguish between working on a connection vs listen socket.

And conversely rename `to` variables to `so` for consistency.

Better diff with the --word-diff --word-diff-regex='\w+' options.

Conflicts:
	bin/varnishd/cache/cache_acceptor.c

It is a 1:1 mapping with IPPROTO_TCP, so TCP_NODELAY was moved down to
be with the other IPPROTO_TCP options.

Conflicts:
	bin/varnishd/cache/cache_acceptor.c