libnl: handle all installed libraries

libnl does not only install libnl.so, but also libnl-nf.so,
libnl-genl.so and libnl-route.so. Change the post-install
and uninstall hooks to handle these libraries as well.

Signed-off-by: Sven Neumann <s.neumann@raumfeld.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>