contrib/liboping.spec: Added example spec file.

contrib/liboping.spec: Added example spec file.

I'm using collectd and the ping plugin for a project I'm working on. I noticed
that collectd is distributing a starter spec file for building RPMs but that
there wa s no such spec file for liboping. I created one which I have attached
to this email. I'm not too familiar with creating RPMs but I think it's a good
start and I was able to get a package built and installed using it. I'm giving
it to you so if you wish to put in on your website for others to start with
when creating packages t hen you may. I hope others may find this useful.