Until such time as Rick Jones can figure-out or be told how to make it
automagic in the configure script, prior to configure on solaris, you
may need:

CFLAGS="-lsocket -lnsl -lkstat"

and if you are trying to compile the SCTP tests:

CFLAGS="-lxnet -lsocket -lnsl -lkstat -D_XOPEN_SOURCE=500 -D__EXTENSIONS__"

beware CPU util figures on anything before Solaris 10 that does not
say 100%, and still be a triffle cautious with Solaris 10 CPU util
reports.