stunnel: fix download url

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/stunnel/stunnel.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 STUNNEL_VERSION = 4.55
-STUNNEL_SITE = http://ftp.nluug.nl/pub/networking/stunnel
+STUNNEL_SITE = http://ftp.nluug.nl/pub/networking/stunnel/archive/4.x/
 STUNNEL_DEPENDENCIES = openssl
 STUNNEL_CONF_OPT = --with-ssl=$(STAGING_DIR)/usr --with-threads=fork
 STUNNEL_LICENSE = GPLv2+