$NetBSD$

DESTDIR support

--- Makefile.orig	2018-07-23 07:03:49.000000000 +0000
+++ Makefile
@@ -12,7 +12,7 @@ doc:
 	ocamldoc -d doc/ -html ptmap.mli
 
 install: all
-	obuild install
+	obuild install --destdir=${DESTDIR}${PREFIX}/${OCAML_SITELIBDIR}
 
 uninstall:
 	ocamlfind -remove ptmap