Add new layout for packages that missing specfile
Some packages are missing some files that are essential for other
layouts. For example specfile(s). Rpkg detects these packages
and assigns the layout to them. It allows 'retire' command for these
packages.
JIRA: RHELCMP-2682
Resolves: rhbz#1885771
Signed-off-by: Ondrej Nosek <onosek@redhat.com>