dhcpcd: switching off or down-priorising SLAAC addresses

[is%netbsd.org@localhost]

I noticed that for dhcpcd using clients, they get the
SLAAC-address/64 and additionally the dhcp-assigned/128 

Now, for some uses, I'd like (e.g. servers) to use ONLY the 
dhcp-assigned address, also for outgoing TCP connections.

If I recall correctly, this used to work with ISC's dhclient.

Any idea how to do this?

(This is netbsd-9.3 with the bundled dhcpcd - 8.1.9. I think I have
the same effect with debian-10 and -11's dhcpcd version.)

	-is