fix testsuite makefile: openbsd does not support PWD env variable

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14340 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
mergeinfo stuff that I don't understand

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14341 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02