Suggestion: get rid of ddhcpdctl and use uc instead saving space in the image

[christf]

We could replace ddhcpctl with uc from https://github.com/christf/uc.git saving some space in the image and further modularizing our builds.
uc is more generic and also used by prefixd and can be used for diagnostics together with l3roamd.

echo get_blocks | uc /tmp/ddhcpd_ctl

ddhcpd requires a different input format at the moment, this change would have implications on the design of the socket. In the code is a TODO for it to be redesigned. This could be an option.

[sargon]

Yes, we could redesign the socket that way. But I would still provide a then adopted ddhcpdctl here.
But then we don't need to package in gluon.