see https://github.com/varnishcache/varnish-cache/pull/3804 for context

The C compiler checks have been removed as they are already
contained in VARNISH_PREREQ

Avoid permissions issues with the UDS in permutations*.vtc.

See merge request uplex-varnish/libvdp-pesi!2

We've had reports of these tests failing on some platforms (e.g.
FreeBSD 13), with FetchError reporting EPERM for the backend that
accesses the UDS.

Since it's not a pesi issue, and not related to the properties under
test, we might as well allow fully open access to the UDS.

make check runs varnishtest with -b 2m.

See merge request uplex-varnish/libvdp-pesi!1

Despite the filtering, the output of permutations.vtc is now over
the 1 MB default limit.

VSC_main.h has moved

Spotted by: jw

To terminate a subrequest, we need to do two things:

- fini the task (signal that the thread handling the subrequest in
  parallel is about to terminate)

- signal that the node representing the subrequest can be picked up by
  esi_level 0 delivery

From the perspective of delivery (unpending), the former needs to
happen before the latter (delivery needs to be sure that no other
thread is working on the node), so we call task_fini() before
signalling that the node done status has changed.

The top level delivery thread, however, might need to tear down the
tree, which assumes that all subrequests have finished. For this, it
checks the task list and waits for it to become empty.

The assumption was that when this is the case, the tree can not be in
use any more, however it could be in vped_task() between task_fini and
releasing the tree lock.

We solve this race by taking the tree lock before finally destroying
it.

Fixes https://gitlab.com/uplex/varnish/libvdp-pesi/-/issues/2

Previously, we accessed struct storage which is private to steverdores.

Thank you to Martin Blix Grydeland for pointing out this improvement
opportunity.

I had removed these before the public open source release based on Flexelint output,
but Geoff is correct that, contrary to the C version macros like __STDC_VERSION__,
_POSIX_C_SOURCE is to be set by the programmer.

Ref: https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html

On the downside, we do now see some noise from flexelint and it is unclear to me
how to suppress Note 9071.

--- Module:   pesi.c (C)
File pesi.c, Line 33
        _
    Note 9071: defined macro '_POSIX_C_SOURCE' is reserved to the compiler
File /usr/include/x86_64-linux-gnu/bits/types/struct_tm.h, Line 23
                      _
  long int __tm_gmtoff;		/* Seconds east of UTC.  */
    Error 114: Inconsistent structure declaration for tag 'tm'
File /usr/include/x86_64-linux-gnu/bits/types/struct_tm.h, Line 24
                       _
  const char *__tm_zone;	/* Timezone abbreviation.  */
    Error 114: Inconsistent structure declaration for tag 'tm'

--- Module:   vdp_pesi.c (C)
File vdp_pesi.c, Line 33
        _
    Note 9071: defined macro '_POSIX_C_SOURCE' is reserved to the compiler
File /usr/include/x86_64-linux-gnu/bits/types/struct_tm.h, Line 23
                      _
  long int __tm_gmtoff;		/* Seconds east of UTC.  */
    Error 114: Inconsistent structure declaration for tag 'tm'
File /usr/include/x86_64-linux-gnu/bits/types/struct_tm.h, Line 24
                       _
  const char *__tm_zone;	/* Timezone abbreviation.  */
    Error 114: Inconsistent structure declaration for tag 'tm'

Thank you, OTTO

Ref varnish-cache fd72157cd52e974d42dff2260cb608a79f1b9403