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.

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

Change-Id: I6b237ecf55ff440b5f5c956ee849a1927bb15441

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

@@ -73,6 +73,18 @@ exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
 import_exceptions =
   oslo_db._i18n
 
+[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
+
 [testenv:lower-constraints]
 basepython = python3
 deps =