From 9b4070944578336506cd0a76de6f733c72d0ca74 Mon Sep 17 00:00:00 2001
From: "Yann E. MORIN" <yann.morin.1998@free.fr>
Date: Sat, 13 Oct 2018 11:11:15 +0200
Subject: [PATCH] configure: fix detection of re-entrant resolver functions

Fixes https://issues.asterisk.org/jira/browse/ASTERISK-21795

uClibc does not provide res_nsearch:
asterisk-16.0.0/main/dns.c:506: undefined reference to `res_nsearch'

Patch coded by Yann E. MORIN:
http://lists.busybox.net/pipermail/buildroot/2018-October/232630.html

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
---
 configure.ac | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/configure.ac
+++ b/configure.ac
@@ -1496,7 +1496,11 @@ AC_LINK_IFELSE(
 			#include <arpa/nameser.h>
 			#endif
 			#include <resolv.h>],
-			[int foo = res_ninit(NULL);])],
+			[
+				int foo;
+				foo = res_ninit(NULL);
+				foo = res_nsearch(NULL, NULL, 0, 0, NULL, 0);
+			])],
 	AC_MSG_RESULT(yes)
 	AC_DEFINE([HAVE_RES_NINIT], 1, [Define to 1 if your system has the re-entrant resolver functions.])
 	AC_SEARCH_LIBS(res_9_ndestroy, resolv)