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.

2 files changed, 1 insertions, 17 deletions

diff --git a/src/Makefile.in b/src/Makefile.in
index 99394ac57cf..8dcaf7e4759 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -302,9 +302,6 @@ CM_OBJ=@CM_OBJ@
 
 LIBGPM = @LIBGPM@
 
-## -lresolv, or empty.
-LIBRESOLV = @LIBRESOLV@
-
 LIBSELINUX_LIBS = @LIBSELINUX_LIBS@
 
 LIBGNUTLS_LIBS = @LIBGNUTLS_LIBS@
@@ -485,7 +482,7 @@ LIBES = $(LIBS) $(W32_LIBS) $(LIBS_GNUSTEP) $(LIBX_BASE) $(LIBIMAGE) \
    $(WEBKIT_LIBS) \
    $(LIB_EACCESS) $(LIB_FDATASYNC) $(LIB_TIMER_TIME) $(DBUS_LIBS) \
    $(LIB_EXECINFO) $(XRANDR_LIBS) $(XINERAMA_LIBS) $(XFIXES_LIBS) \
-   $(LIBXML2_LIBS) $(LIBGPM) $(LIBRESOLV) $(LIBS_SYSTEM) $(CAIRO_LIBS) \
+   $(LIBXML2_LIBS) $(LIBGPM) $(LIBS_SYSTEM) $(CAIRO_LIBS) \
    $(LIBS_TERMCAP) $(GETLOADAVG_LIBS) $(SETTINGS_LIBS) $(LIBSELINUX_LIBS) \
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) \
diff --git a/src/process.c b/src/process.c
index f40e8e53a24..85a4885bbf4 100644
--- a/src/process.c
+++ b/src/process.c
@@ -75,11 +75,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 # include <sys/stropts.h>
 #endif
 
-#ifdef HAVE_RES_INIT
-#include <arpa/nameser.h>
-#include <resolv.h>
-#endif
-
 #ifdef HAVE_UTIL_H
 #include <util.h>
 #endif
@@ -3827,10 +3822,6 @@ usage: (make-network-process &rest ARGS)  */)
       immediate_quit = 1;
       QUIT;
 
-#ifdef HAVE_RES_INIT
-      res_init ();
-#endif
-
       struct addrinfo hints;
       memset (&hints, 0, sizeof hints);
       hints.ai_family = family;
@@ -3910,10 +3901,6 @@ usage: (make-network-process &rest ARGS)  */)
       immediate_quit = 1;
       QUIT;
 
-#ifdef HAVE_RES_INIT
-      res_init ();
-#endif
-
       host_info_ptr = gethostbyname ((const char *) SDATA (host));
       immediate_quit = 0;