Stop calling res_init
Emacs shouldn’t need to call res_init any more, now that nscd or
equivalent is everywhere. On modern systems, calling res_init
simply slows Emacs down. On ancient systems lacking nscd Emacs
will still work well enough with this change; it’s just that it
won’t respond to changes in /etc/resolv.conf.
* configure.ac (HAVE_RES_INIT): Remove. Worry about -lresolv only
when configured --with-hesiod. Hesiod is still used; see, e.g.:
https://soylentnews.org/meta/article.pl?sid=15/07/13/
0255214
* src/Makefile.in (LIBRESOLV): Remove. All uses removed.