Add local bindep.txt

As it was announced [1] global bindep-fallback.txt was removed and now
projects need to have a local bindep.txt to be able to install binary
dependencies for testing.

In test jobs the script tools/test-setup.sh is called which requires
mysql and postgres servers and clients to be installed.

Conflicts:
      tox.ini

[1] http://lists.openstack.org/pipermail/openstack-discuss/2019-June/007272.html

Change-Id: I6b237ecf55ff440b5f5c956ee849a1927bb15441
(cherry picked from commit f34e53ebf7)
(cherry picked from commit 67904312ab)
(cherry picked from commit d37a0eb3d5)

bindep.txt

@@ -0,0 +1,8 @@
+# This is a cross-platform list tracking distribution packages needed for install and tests;
+# see https://docs.openstack.org/infra/bindep/ for additional information.
+
+mysql-client [platform:dpkg]
+mysql-server [platform:dpkg]
+postgresql
+postgresql-client [platform:dpkg]
+

tox.ini

@@ -72,3 +72,15 @@ import_exceptions =
 # of the requirements.txt files
 deps = pip_missing_reqs
 commands = pip-missing-reqs -d --ignore-module=oslo_db* --ignore-module=pkg_resources --ignore-file=oslo_db/tests/* oslo_db
+
+[testenv:bindep]
+basepython = python3
+# Do not install any requirements. We want this to be fast and work even if
+# system dependencies are missing, since it's used to tell you what system
+# dependencies are missing! This also means that bindep must be installed
+# separately, outside of the requirements files, and develop mode disabled
+# explicitly to avoid unnecessarily installing the checked-out repo too (this
+# further relies on "tox.skipsdist = True" above).
+deps = bindep
+commands = bindep test
+usedevelop = False