[network-manager-libreswan] build: fix linking against libdl.so for dlopen()

[Thomas Haller <thaller src gnome org>]

commit 9d337b1d70bb42adff18552bcec6720379cb6235
Author: Thomas Haller <thaller redhat com>
Date:   Wed Sep 7 18:15:51 2016 +0200

    build: fix linking against libdl.so for dlopen()

 configure.ac           |    3 +++
 properties/Makefile.am |    4 +++-
 2 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 31a96c8..89f4fe5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,6 +42,9 @@ AC_PROG_GCC_TRADITIONAL
 AC_FUNC_MEMCMP
 AC_CHECK_FUNCS(select socket uname)
 
+AC_SEARCH_LIBS([dlopen], [dl dld], [], [ac_cv_search_dlopen=])
+AC_SUBST([DL_LIBS], "$ac_cv_search_dlopen")
+
 dnl ensure that when the Automake generated makefile calls aclocal,
 dnl it honours the $ACLOCAL_FLAGS environment variable
 ACLOCAL_AMFLAGS="\${ACLOCAL_FLAGS}"
diff --git a/properties/Makefile.am b/properties/Makefile.am
index e2c4fa9..8591743 100644
--- a/properties/Makefile.am
+++ b/properties/Makefile.am
@@ -43,7 +43,9 @@ libnm_vpn_plugin_libreswan_la_SOURCES = \
     $(plugin_sources)
 
 libnm_vpn_plugin_libreswan_la_LIBADD = \
-    $(LIBNM_LIBS)
+    $(LIBNM_LIBS) \
+    $(LD_LIBS) \
+    $(NULL)
 
 libnm_vpn_plugin_libreswan_la_LDFLAGS = \
     -avoid-version \