acme: add dns_wait option

acme.sh by default use public DNS resolvers to check if TXT record was
correctly added when using DNS-01. This can be undesirable in a private
environment where the DNS server is not publicly accessible.

This option allows bypassing such check and simply waiting for a
specific length of time for the TXT record to take effect.

Signed-off-by: Glen Huang <i@glenhuang.com>

net/acme-acmesh/files/hook.sh

@@ -87,6 +87,9 @@ get)
 		elif [ "$calias" ]; then
 			set -- "$@" --challenge-alias "$calias"
 		fi
+		if [ "$dns_wait" ]; then
+			set -- "$@" --dnssleep "$dns_wait"
+		fi
 	elif [ "$standalone" = 1 ]; then
 		set -- "$@" --standalone --listen-v6
 	else