package/vtun: fix static linking with atomic

Fixes:
 - http://autobuild.buildroot.org/results/908707cdd16c5b89197c226a3e259f8943a5474e

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit cff14017f99c6c8a85784a0f1b2e39f3094ed162)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/vtun/vtun.mk

@@ -8,7 +8,7 @@ VTUN_VERSION = 3.0.4
 VTUN_SITE = http://downloads.sourceforge.net/project/vtun/vtun/$(VTUN_VERSION)
 VTUN_LICENSE = GPL-2.0+ with OpenSSL exception
 VTUN_LICENSE_FILES = README.OpenSSL
-VTUN_DEPENDENCIES = host-bison host-flex zlib lzo openssl
+VTUN_DEPENDENCIES = host-bison host-flex host-pkgconf zlib lzo openssl
 VTUN_AUTORECONF = YES
 
 VTUN_CONF_OPTS = \
@@ -19,4 +19,8 @@ VTUN_CONF_OPTS = \
 # Assumes old-style gcc inline symbol visibility rules
 VTUN_CONF_ENV = CFLAGS="$(TARGET_CFLAGS) -std=gnu89"
 
+# configure.in forgets to link to dependent libraries of openssl breaking static
+# linking
+VTUN_CONF_ENV += LIBS=`$(PKG_CONFIG_HOST_BINARY) --libs openssl`
+
 $(eval $(autotools-package))