rwtab: Add /var/lib/ovirt-hosted-engine-setup

engine-setup needs to write answer.conf into
/var/lib/ovit-hosted-engine-setup/answers without making
the directory rw it will fail.

Change-Id: I50a6f8dea419f296a23940727827c5fd14f73375
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>