Fix configure with security/libassuan 3.x

--- configure.orig	2018-10-16 21:44:05 UTC
+++ configure
@@ -2256,8 +2256,8 @@ NEED_GPG_ERROR_VERSION=1.27
 
 
 NEED_GPG_ERROR_VERSION=1.27
-NEED_LIBASSUAN_API=2
-NEED_LIBASSUAN_VERSION=2.4.2
+NEED_LIBASSUAN_API=3
+NEED_LIBASSUAN_VERSION=3.0.0
 NEED_GPGME_API=1
 NEED_GPGME_VERSION=1.9.0