Hi Guix,

here's another batch of LV2-related patches.  They depend on some of the
previous patches[1] and on the waf-build-system[2].

This patch set adds the following libraries, all of which are
dependencies of Ardour (and possibly other LV2 hosts):

- serd
- sord
- sratom
- lilv
- suil

~~ Ricardo

[1]: http://lists.gnu.org/archive/html/guix-devel/2015-01/msg00446.html
[2]: http://lists.gnu.org/archive/html/guix-devel/2015-01/msg00439.html