package/stunnel: requires DES support in openssl

Enable DES in openssl to fix build failure raised since commit
a83d41867c8d69a77d5cd0a665aa216af5340359

Fixes:
 - http://autobuild.buildroot.org/results/4b306a13f543bbabf3f01d882b3549e3d9961556

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/stunnel/Config.in

@@ -2,6 +2,7 @@ config BR2_PACKAGE_STUNNEL
 	bool "stunnel"
 	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_OPENSSL
+	select BR2_PACKAGE_LIBOPENSSL_ENABLE_DES if BR2_PACKAGE_LIBOPENSSL
 	help
 	  Stunnel is a program that wraps any TCP connection with an SSL
 	  connection.