Fix gate error "mysqladmin: command not found"

mysqladmin package is required in tools/test-setup.sh
so adding bindep.txt file for this binary dependencies

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

Change-Id: I469a04220ad36451d155a5256926d992aa56b5c3

bindep.txt

@@ -0,0 +1,10 @@
+# This is a cross-platform list tracking distribution packages needed by tests;
+# see http://docs.openstack.org/infra/bindep/ for additional information.
+
+gettext [test]
+
+mysql-client [platform:dpkg]
+mysql-server [platform:dpkg]
+postgresql
+postgresql-client [platform:dpkg]
+postgresql-server [platform:rpm]

tox.ini

@@ -106,3 +106,14 @@ deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
+
+[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