Support Oracle Linux 5.x

Oracle Linux 5, also known as Unbreakable Linux is currently
not supported by salt.

This one line fix solves this issue.

For reference, the os info extracted through platform.linux_distribution()
python call:
('Enterprise Linux Enterprise Linux Server', '5.1', 'Carthage')
Merge pull request #9019 from blackduckx/develop

Support Oracle Linux 5.x