Update login.defs on openSUSE

Some of the tripleo image elements rely useradd a for creating a group
with the same name as the user that is added. On openSUSE is feature
is turned off by default. So enable it here.

Change-Id: I120067e5e522dc6e704e7f09b724d60dee0c7f22
Merge "Update login.defs on openSUSE"