OpenEmbedded "poky" with some sysmocom specific modifications. Mostly used only up to sysmocom release 201310, but the "pyro" branch is still used for 201705
So far we have used chrpath to fix the rpath we don't want but
this creates issues with supporting both dora and edison (we need
to depend on different recipes). Instead just force the RPATH to
be off. This can be done by setting the internal _RPATH variable.
I found this in Tool/gnulink.py.