acme: Fix for curl linked against mbed TLS. (#4254)

Use newest acme.sh release (2.6.8).
Remove dependency on ca-certificates and add dependency on ca-bundle.
Update environment variable.

Signed-off-by: Daniel Halmschlager <da@halms.at>

Backport to 17.01 for compatibility with 17.01.2, but keep the old envvar so
it'll hopefully keep working for users who haven't upgraded.

Closes #4579, closes #4699.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

net/acme/Makefile

@@ -8,8 +8,8 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=acme
-PKG_SOURCE_VERSION:=6d84da588b98733dd9c4f5b88440281ab1eb4989
+PKG_SOURCE_VERSION:=7b40cbe8c1a52041351524bcde4b37665a7cdf79
-PKG_VERSION:=1.4
+PKG_VERSION:=1.5
 PKG_RELEASE:=1
 PKG_LICENSE:=GPLv3
 
@@ -25,7 +25,7 @@ include $(INCLUDE_DIR)/package.mk
 define Package/acme
   SECTION:=net
   CATEGORY:=Network
-  DEPENDS:=+curl +ca-certificates +openssl-util +netcat
+  DEPENDS:=+curl +ca-bundle +openssl-util +netcat
   TITLE:=ACME (Letsencrypt) client
   PKGARCH:=all
   MAINTAINER:=Toke Høiland-Jørgensen <toke@toke.dk>

net/acme/files/run.sh

@@ -10,7 +10,11 @@
 
 CHECK_CRON=$1
 ACME=/usr/lib/acme/acme.sh
+# We export both ca variables in an attempts to keep backwards
+# compatibility with older versions of curl that was linked against
+# openssl
 export SSL_CERT_DIR=/etc/ssl/certs
+export CURL_CA_BUNDLE=/etc/ssl/certs/ca-certificates.crt
 export NO_TIMESTAMP=1
 
 UHTTPD_LISTEN_HTTP=