Also generallize the yp_dbwrite functions a little: allow the caller
to specify certain flags. I need this mostly for some changes to
rpc.yppasswdd to allow in-place updates.
Also change Makefile a little to use the same format as ypserv.
to the old one, except that it supports an additional option (-p path)
that lets you specify the top level path wiere your NIS maps live.
(ypserv allows you to specify a path like this, so it makes sense that
ypxfr should too. ypserv will automagically pass the -p flag to ypxfr
if you use a path other than /var/yp when you start it.)
This program uses client stub code generated by rpcgen as well as
the yp_dblookup.c module from ypserv.
