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"

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

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

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.

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

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.

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

Closes #3692

When decoding only a substring, we naturally see no padding, so we must
not base tail processing on the number of pad characters seen, but
rather on the number of characters missing until the end of the current
block of four.

Fixes #3378

Conflicts:
	.travis.yml
	bin/varnishd/cache/cache_panic.c

When a VUT is slow enough, it might very well be overrun while it is
scanning logs. For our built-in VUTs like varnishncsa or varnishlog
this can happen if writing the output can block waiting for IO ops
or when the output is piped to a slow consumer.

There's only one call site for vtx_dispatch() and it guarantees that len
is greater than zero.

A default stack space of 48k will cause a stack overflow in some of
the test cases on some Linux distributions. The increase to 64k seems
to be enough to solve this.

Fixes #3437

0051cbe3 did not work on
solaris-descendents, the man page clearly states that the size argument
also determines the buffer to be malloc()ed for a NULL buffer argument.

Ever since my system upgraded haproxy to 2.3.10 this test has
consistently timed out. While that would be a breaking change
involving the independent vtest project too, I think the VTC
syslog spec would work better with something like:

    expect skip facility.level regex

Where skip could be uint, * or ? similar to how logexpect works,
and both facility and level could also be * to be non-specific.
For now, let's hope this does not break the test suite for anyone
else.

Conflicts:
	bin/varnishtest/tests/h00005.vtc

In the output of vcl.show -v, it means that the least useful file (in the
sense that it is common to every single vcl.load) is now printed last.

This change originates from a larger and more intrusive refactoring.

It also helps get rid of spurious Wstring-contatenation warnings from
clang 12 in the test suite, instead of disabling it altogether.

Refs c8174af6

 Conflicts:
	bin/varnishd/cache/cache_esi_deliver.c

This is just the order of their declaration in the VCL manual.

As a side effect it works around a bug where the sess.xid syntax
requirements would prevent sess.timeout_idle to be used in VCL 4.0,
which is less intrusive than a proper fix.

The bug was fixed in trunk without being noticed in the first place
after many heavy changes to libvcc. For a stable branch this is less
risky than a back-port since there are only two sess.* symbols.

Fixes #3564

When receiving H/2 data frames, make sure to take the advertised content
length into account, and fail appropriately if the combined sum of the
data frames does not match the content length.

The change to VTCP_Check() in 58a21da7
broke expect_close in varnishtest.