rpm: make ceph-common own the new denc directory

rpm: make ceph-common own the new denc directory

2d3c6561b4ac1473a728e81c232d7dfe6fc0188c introduced a new library directory
"%{_libdir}/ceph/denc/" in ceph-common but did not explicitly state that it
should be owned by the package. This caused OBS builds to fail as follows:

[ 5515s] ceph-common-17.0.0-2786.1.x86_64.rpm: directories not owned by a package:
[ 5515s]  - /usr/lib64/ceph/denc

Fixes: 2d3c6561b4ac1473a728e81c232d7dfe6fc0188c
Signed-off-by: Nathan Cutler <ncutler@suse.com>
(cherry picked from commit de6c8250a6d91403e6d334aeb901bf9720ba40eb)