Merge branch 'tools-ynl-gen-dust-off-the-user-space-code'

Jakub Kicinski says:

====================
tools: ynl-gen: dust off the user space code

Every now and then I wish I finished the user space part of
the netlink specs, Python scripts kind of stole the show but
C is useful for selftests and stuff which needs to be fast.
Recently someone asked me how to access devlink and ethtool
from C++ which pushed me over the edge.

Fix things which bit rotted and finish notification handling.
This series contains code gen changes only. I'll follow up
with the fixed component, samples and docs as soon as it's
merged.
====================

Link: https://lore.kernel.org/r/20230602023548.463441-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>