acme: fix the 'Unknown parameter' problem caused by acme_server

Signed-off-by: Meano <meano@foxmail.com>

net/acme/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=acme
 PKG_VERSION:=2.8.7
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/acmesh-official/acme.sh/tar.gz/$(PKG_VERSION)?

net/acme/files/run.sh

@@ -279,7 +279,7 @@ issue_cert()
 	[ -n "$ACCOUNT_EMAIL" ] && acme_args="$acme_args --accountemail $ACCOUNT_EMAIL"
 	[ "$use_staging" -eq "1" ] && acme_args="$acme_args --staging"
 
-	if [ -n $acme_server ]; then
+	if [ -n "$acme_server" ]; then
 		log "Using custom ACME server URL"
 		acme_args="$acme_args --server $acme_server"
 	fi