Add compatibility for new location of unix

Author: dra27

bootstrap

@@ -1,11 +1,11 @@
 #!/usr/bin/env bash
 
 libs="unix.cmxa"
-OCAMLOPT="ocamlopt -g"
+OCAMLOPT="ocamlopt -g -I +unix"
 # use faster ocamlopt, if available
 OCAMLOPT_OPT=`which ocamlopt.opt`
 if [[ $OCAMLOPT_OPT != "" ]] ; then
-    OCAMLOPT="ocamlopt.opt -g"
+    OCAMLOPT="ocamlopt.opt -g -I +unix"
 fi
 OCAMLVER=`$OCAMLOPT -vnum`
 echo $OCAMLVER