with nathan_sa branch merged to the HEAD, we need to upgrade
	our resolver library to be thread safe.  i have been thinking
	about it for a long time, and the conclusion is that we really need
	to switch to bind8 resolver all the way through.  some suggested that
	we can just switch res_* and keep using nsdispatch(), but i don't think
	it possible.  in addition to res_*, we need to make:
	- *hostent thread safe,
	- *servent thread safe, and
	- all NIS lookups thread safe.
	redoing it all by ourselves does not look feasible, or even remotely
	possible.

itojun