dhcp: fix build issue with libxml2 support

A missing case breaks the build when libxml2 is
required and found appropriately. The third argument
to the function AC_SEARCH_LIB is action-if-found which
was mistakenly been used for the case where the library
is not found and hence breaks the configure phase
where it shoud actually pass.
We now pass on silently when action-if-found is
executed.

(From OE-Core rev: a17f3ec910366e9e7551fa24fbc07929b9584341)

Signed-off-by: Awais Belal <awais_belal@mentor.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-connectivity/dhcp/dhcp/0012-dhcp-correct-the-intention-for-xml2-lib-search.patch

@@ -0,0 +1,37 @@
+From 501543b3ef715488a142e3d301ff2733aa33eec7 Mon Sep 17 00:00:00 2001
+From: Awais Belal <awais_belal@mentor.com>
+Date: Wed, 25 Oct 2017 21:00:05 +0500
+Subject: [PATCH] dhcp: correct the intention for xml2 lib search
+
+A missing case breaks the build when libxml2 is
+required and found appropriately. The third argument
+to the function AC_SEARCH_LIB is action-if-found which
+was mistakenly been used for the case where the library
+is not found and hence breaks the configure phase
+where it shoud actually pass.
+We now pass on silently when action-if-found is
+executed.
+
+Upstream-Status: Pending
+
+Signed-off-by: Awais Belal <awais_belal@mentor.com>
+---
+ configure.ac | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/configure.ac b/configure.ac
+index bfe988a..f0459e6 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -608,7 +608,7 @@ AC_ARG_WITH(libxml2,
+ 	with_libxml2="$withval", with_libxml2="no")
+ 
+ if test x$with_libxml2 != xno; then
+-	AC_SEARCH_LIBS(xmlTextWriterStartElement, [xml2],
++	AC_SEARCH_LIBS(xmlTextWriterStartElement, [xml2],,
+ 		[if test x$with_libxml2 != xauto; then
+ 			AC_MSG_FAILURE([*** Cannot find xmlTextWriterStartElement with -lxml2 and libxml2 was requested])
+ 		fi])
+-- 
+2.11.1
+

meta/recipes-connectivity/dhcp/dhcp_4.3.6.bb

@@ -11,6 +11,7 @@ SRC_URI += "file://0001-define-macro-_PATH_DHCPD_CONF-and-_PATH_DHCLIENT_CON.pat
             file://0009-remove-dhclient-script-bash-dependency.patch \
             file://0010-build-shared-libs.patch \
             file://0011-Moved-the-call-to-isc_app_ctxstart-to-not-get-signal.patch \
+            file://0012-dhcp-correct-the-intention-for-xml2-lib-search.patch \
            "
 
 SRC_URI[md5sum] = "afa6e9b3eb7539ea048421a82c668adc"