instead of the kernel. dhcpcd will only do this if RA is disabled in the kernel
or dhcpcd has been instructed to do this via dhcpcd.conf(5) ipv6ra_own and
ipv6ra_own_default directives.
Send and process IPv6 Neighbor Solicitions and Adverts to prove router
reachability. If a router cannot be reached in this way then it is expired.
When debugging, all ND messages are displayed which will create a lot of log
spam.
To ease packaging, ./configure now accepts LDFLAGS and --enable-static.