Please backport libzstd 1.2.0-1 (universe) from artful

[Yann Collet]

Please backport libzstd 1.2.0-1 (universe) from artful to zesty.

Reason for the backport:
========================
Current version in Xenial is v0.5.1,
it's an experimental version, using its own, incompatible format.
As a consequence, zstd on Ubuntu Xenial is not compatible with the rest of the world.

This is of important concern for products using libzstd as a shared library :
on Ubuntu Xenial, produced data is different, not compatible with v1+.

This issue has been made more pressing with the integration of zstd in Linux Kernel,
as userland tools must also be updated to read and generate zstd.

Testing:
========
Mark off items in the checklist [X] as you test them, but please leave the checklist so that backporters can quickly evaluate the state of testing.

You can test-build the backport in your PPA with backportpackage:
$ backportpackage -u ppa:<lp username>/<ppa name> -s artful -d zesty libzstd

* zesty:
[ ] Package builds without modification
[ ] zstd installs cleanly and runs
[ ] zstd-dbgsym installs cleanly and runs
[ ] libzstd1-dbgsym installs cleanly and runs
[ ] libzstd-dev installs cleanly and runs
[ ] libzstd1 installs cleanly and runs

Reverse dependencies:
=====================
The following reverse-dependencies need to be tested against the new version of libzstd. For reverse-build-dependencies (-Indep), please test that the package still builds against the new libzstd. For reverse-dependencies, please test that the version of the package currently in the release still works with the new libzstd installed. Reverse- Recommends, Suggests, and Enhances don't need to be tested, and are listed for completeness-sake.

zstd
----
* check-all-the-things
  [ ] zesty (Reverse-Recommends)

zstd-dbgsym
-----------

libzstd-dev
-----------
* c-blosc
  [ ] zesty (Reverse-Build-Depends)
* pytables
  [ ] zesty (Reverse-Build-Depends)
* groonga
  [ ] zesty (Reverse-Build-Depends)

libzstd1
--------
* libblosc1
  [ ] zesty (Reverse-Depends)
* libgroonga0
  [ ] zesty (Reverse-Depends)

libzstd1-dbgsym
---------------

[Yann Collet (cyan4973)]

I don't understand why this request is labelled "zesty".

The request is for "xenial", aka LTS 16.04.

It was created with `requestbackport` from an Ubuntu Xenial machine.

[Yann Collet (cyan4973)]

Superceded by https://bugs.launchpad.net/bugs/1717040