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

[Thomas Haller <thaller src gnome org>]

commit 665f15c52898a5019a0292cb1a52c232bc81ff60
Author: Thomas Haller <thaller redhat com>
Date:   Wed Sep 7 19:02:32 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 dd432f6..a18765d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -39,6 +39,9 @@ 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 c206ac2..438423c 100644
--- a/properties/Makefile.am
+++ b/properties/Makefile.am
@@ -48,7 +48,9 @@ libnm_vpn_plugin_openconnect_la_CFLAGS = \
 
 libnm_vpn_plugin_openconnect_la_LIBADD = \
        $(LIBNM_LIBS) \
-       $(OPENCONNECT_LIBS)
+       $(OPENCONNECT_LIBS) \
+       $(DL_LIBS) \
+       $(NULL)
 
 libnm_vpn_plugin_openconnect_la_LDFLAGS = \
        -avoid-version \