Please backport libnss-cache 0.16-3 (universe) from zesty

[Bradley Baetz]

Please backport libnss-cache 0.16-3 (universe) from zesty to trusty, xenial, yakkety.

Reason for the backport:
========================
libnss-cache was backported in https://bugs.launchpad.net/trusty-backports/+bug/1323161 to support multi-arch. However, this change was buggy and doesn't support multi-arch properly since the packages install files directly into /usr/lib/ and so aren't parallel installable. This has been fixed in newer versions.

Since this is an NSS module, its needed by both amd64 and i386 libcs when its configured, otherwise NSS lookups don't work, so not being parallel installable means that 32-bit binaries don't work.

I'm not sure if the xenial/yakkety versions should be handled as bugfixes rather than a backport?

The specific fixes needed are:

https://github.com/google/libnss-cache/commit/ed1f7100850123c053e6e4265b6365e8a46f4f06
https://github.com/google/libnss-cache/commit/8ed924a410a471bc501bcad54b3e463284bd7726

but all the other fixes are documentation/packaging/build fixes.

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 zesty -d trusty libnss-cache
$ backportpackage -u ppa:<lp username>/<ppa name> -s zesty -d xenial libnss-cache
$ backportpackage -u ppa:<lp username>/<ppa name> -s zesty -d yakkety libnss-cache

* trusty:
[X] Package builds without modification
[ ] libnss-cache-dbgsym installs cleanly and runs
[X] libnss-cache installs cleanly and runs
* xenial:
[X] Package builds without modification
[ ] libnss-cache-dbgsym installs cleanly and runs
[ ] libnss-cache installs cleanly and runs
* yakkety:
[X] Package builds without modification
[ ] libnss-cache-dbgsym installs cleanly and runs
[ ] libnss-cache installs cleanly and runs

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

libnss-cache
------------
* nsscache
  [ ] trusty (Reverse-Recommends)
  [ ] xenial (Reverse-Recommends)
  [ ] yakkety (Reverse-Recommends)

libnss-cache-dbgsym
-------------------