Include autoconf files for opensaml2

diff --git a/shibboleth/opensaml2 b/shibboleth/opensaml2
index 38aa315..18d1f38 160000 (submodule)
--- a/shibboleth/opensaml2
+++ b/shibboleth/opensaml2
@@ -1 +1 @@
-Subproject commit 38aa315e2be9d5e9239e4a2754310cdfcfd2cf45
+Subproject commit 18d1f3824aabfb06bfbcbbc7845ca2f3cddd4c9f