Fixes #3882

Otherwise a long banner may throw expectations off by one line.

Fixes #3877

Neither Martin nor I can remember why this was uintptr_t in the first
place, and there is no signs of pointers anywhere nearby.

Refs #3874

It makes no sense to emit this just before we end the transaction,
except to help varnishncsa find the client IP address.

Upon success we expect a non-null pointer, and to make sure this is not
residual uninitialized stack memory, it is null'd beforehand.

    /bin/varnishd/cache/cache_acceptor.c: 375 in vca_mk_tcp()
    369     {
    370             struct suckaddr *sa;
    371             ssize_t sz;
    372
    373             AN(SES_Reserve_remote_addr(sp, &sa, &sz));
    374             assert(sz == vsa_suckaddr_len);
    >>>     CID 1517259:  Resource leaks  (RESOURCE_LEAK)
    >>>     Failing to save or free storage allocated by "VSA_Build(sa, &wa->acceptaddr, wa->acceptaddrlen)" leaks it.
    375             AN(VSA_Build(sa, &wa->acceptaddr, wa->acceptaddrlen));
    376             sp->sattr[SA_CLIENT_ADDR] = sp->sattr[SA_REMOTE_ADDR];

It is precisely because we reserve the space to store the built suckaddr
that there won't be a malloc() call made behind our back.

For some reason, it only complained about one call site.

Inspired by: CHERI

Spotted as always: by Dridi

The matching regular expression did not align with the substitution
regular expression.

Refs d2e526ce

Avoid marking an object as an IMS candidate when a weak Last-Modified
header is the only validator. In the case where there is an ETag AND a
weak Last-Modified header, add a If-None-Match header, but do not add
an If-Modified-Since header.

Per RFC9110, the Last-Modified header is not a strong validator unless
it is at least one second older than the Date header. This is to prevent
revalidating content that has been changed within a second of the last
response. In the case of an intermediate cache like Varnish, a weak
Last-Modified validator is "weaker" than a weak ETag, and should not be
used for revalidating content.

This commit prepares varnishtest for a change to Varnish revalidations,
where the Last-Modified header must be at least one second older than
the Date header for Varnish to send an If-Modified-Since header.

Any explicitly defined Date header will override the default, and
the Date header can be omitted with -nodate.

Motivated by #3868

Spotted by GCC's fortification level 3.