libdht: update to 2026-09-01

libdht: update to 2026-09-01

Two fixes to the maintenance and search timers, both of which cost a
node contacts it should have had.

Neighbourhood maintenance for both address families was gated on a
single flag that either family's bucket maintenance could set.  Bucket
maintenance only confirms nodes that are already known, while
neighbourhood maintenance is what grows the table, so a family whose
nodes never answer held back table growth for the other family too.  A
node with no route for one family still holds addresses of that family,
because they arrive in the replies of the other, so this reaches any
single-stack node on a dual-stack build.  Each family is now gated on
its own bucket maintenance, and the number of queries per round is
unchanged.

A search step scheduled for exactly its due second returned without
sending anything, because the comparison required the second to have
passed rather than arrived.  The early return left the step time alone,
so the search then waited another full interval having sent nothing.

Reset PKG_RELEASE, since the source version changed.

Signed-off-by: Daniel Golle <redacted>