Fix lib/oslo to only reference things which exist

The backport of the install from libs infrastructure left some
unwanted bits in lib/oslo that cause cryptic build issues. Remove
that.

Change-Id: If56f64f1305a206e5360ad9b5e3e41db4d60d576
Merge branch 'stable/icehouse' of https://github.com/openstack-dev/devstack into stable/icehouse