Add patch that was missing in the OCaml 4.09.0 update

lang/ocaml-camlp4/patches/patch-configure

@@ -0,0 +1,15 @@
+$OpenBSD: patch-configure,v 1.3 2019/09/26 11:04:50 chrisz Exp $
+camlp4 4.08 seems to work with OCaml 4.09 just fine.
+
+Index: configure
+--- configure.orig
++++ configure
+@@ -39,7 +39,7 @@ if [ $major -lt 4 -o \( $major -eq 4 -a $minor -lt 2 \
+     echo "The standalone Camlp4 requires OCaml >= 4.02."
+     echo "For previous versions of OCaml use the Camlp4 distributed with OCaml."
+     exit 2
+-elif [ $major -ne 4 -o $minor -ne 8 ]; then
++elif [ $major -ne 4 -o $minor -ne 9 -a $minor -ne 8 ]; then
+     echo "This version of Camlp4 is for OCaml 4.07 but you are using OCaml $ocaml_version."
+     if [ -d .git ] ; then
+       if [ $PINNED -eq 1 ] ; then