Add libmysqlservices.a for mysql56u-devel

It is necessary to be installed `libmysqlservices.a` on adding custom plugins.  
I have add the line to `SPECS/mysql56u.spec` same as oracle package like below.

```
$ less ~/rpmbuild/SPECS/mysql.5.6.14.spec
%files -n MySQL-devel%{product_suffix} -f optional-files-devel
%defattr(-, root, root, 0755)
%doc %attr(644, root, man) %{_mandir}/man1/comp_err.1*
%doc %attr(644, root, man) %{_mandir}/man1/mysql_config.1*
%attr(755, root, root) %{_bindir}/mysql_config
%dir %attr(755, root, root) %{_includedir}/mysql
%dir %attr(755, root, root) %{_libdir}/mysql
%{_includedir}/mysql/*
%{_datadir}/aclocal/mysql.m4
%{_libdir}/mysql/libmysqlclient.a
%{_libdir}/mysql/libmysqlclient_r.a
%{_libdir}/mysql/libmysqlservices.a
```

Please let me know if have to use the launchpad instead of GitHub.
ref. http://iuscommunity.org/pages/ContributingToIUS.html