I noticed in the process of trying to draft code to do this that there
will be a lot of code duplication with the resolv.conf parsing in
res_msend.c, and that this code has some stupid bugs (for example it
stops parsing after it gets 3 nameservers, so it might miss options
later in the file), so I think I'll take a look at factoring it into a
new function to gather all the interesting information from
resolv.conf that can be used in both places.

A couple additional things I noticed from resolv.conf(5):

1. The default domain used by glibc is not the dns root but rather the
   domain portion of the local hostname determined by gethostname().
   Is there any value in duplicating this? Does anyone want/need it?

2. It's not clear from the documentation of "search" whether its
   presence overrides/suppresses the "domain" (default or set by
   resolv.conf) or adds additional searches before or after it. Which
   should it do?

While glibc/legacy behavior is worth looking at, I don't think we need
to look at things from a standpoint of exactly duplicating that.
Meeting real-world modern application needs while avoiding
inconveniencing users with stupid/unwanted behavior should be the
primary goal.

Rich