Install system dependencies for tox-molecule

Avoids the need to add complex bindep.txt on each repository that
uses molecule by adding the boostraping of dependencies directly
in the job definition.

This was already tested on CentOS/Fedora/RHEL via
https://review.rdoproject.org/r/#/c/21486/

Change-Id: I2a3b1143b566b31fb866f7c3ecae7ff0276cb246

playbooks/tox/pre-molecule.yaml

@@ -1,3 +1,29 @@
 - hosts: all
-  roles:
-    - install-docker
+  tasks:
+
+  # psutil->python-devel
+  # psutil->gcc
+  # ansible->selinux
+  - name: install packages needed by molecule
+    when: ansible_os_family == "RedHat" and ansible_lsb.major_release|int >= 8
+    become: true
+    package:
+      name:
+        - python2-devel
+        - python2-libselinux
+        - python3-devel
+        - python3-libselinux
+        - gcc
+
+  - name: install packages needed by molecule
+    when: ansible_os_family == "RedHat" and ansible_lsb.major_release|int < 8
+    become: true
+    package:
+      name:
+        - python-devel
+        - libselinux-python
+        - gcc
+
+  - name: install docker
+    include_role:
+      name: install-docker