debugger: do not ask confirmation before quitting

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@14370 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
test/tool-debugger: robustify makefile

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@14371 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02