debugger test: take the correct variant of the Unix library for dynlink

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@14357 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
debugger test portability: use egrep instead of grep

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@14358 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02