Add  _amd64|_arm64 before the extension

For some reason this is failing on some platforms reporting on VTEST.

Mkdtemp(3) creates the directory with mode 0700, and since it
already exists, we do not change the mode subsequently, which
causes jailed with uid=vcache to keel over.

Previously it only did so if no -n argument was given.

Fixes #3307

Add VJ_unlink() and VJ_rmdir() to do so.

Fixes: #3327

and, in particular, matching client.ip against a vcl

Ref #3334

There is a problem with fakeroot-sysv on Ubuntu 20.04 aarch64:

Install Build-Depends packages...

+ mk-build-deps --install debian/control

+ yes

semop(1): encountered an error: Function not implemented

Error in the build process: exit status 1

That is, in the context of varnish.m4, because this changes existing
behavior in a way that breaks backward compatibility.

Partial revert of 134d0633.

This is to support generated vcc files with out-of-tree vmod builds.

our python sources use spaces

In order to build aarch64 packages it relies on the machine executors
feature based on QEMU. Since the same scripts were needed to build
packages for different architectures they were extracted in standalone
shell scripts.

Alpine Linux packages are now built in addition to RPM and Deb packages
but considering how long emulation takes for aarch64 packages, packaging
was moved to a nightly workflow.

Some changes happened in the pkg-varnish-cache repository to accomodate
the CircleCI reorganization, mainly around dependency management.

More information in the CircleCI README file.

Closes #3313
Reviewed-by: Guillaume Quintard <guillaume@varnish-software.com>
Signed-off-by: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>

Ref #3311

See comments in #3311, but done slightly differently

This is an alternative implementation of #2680

Ref #3312

Closes #3312 (probably)

Fixes: #3266