PR#6466: use "extensible variant" rather than "open" types in error message

(Leo White)

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15715 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
testsuite/Makefile.toplevel: make terminal DUMB by default (tests rely on this)

Currently it is not equivalent to do:
  cd testsuite; make one DIR=tests/$foo
and
  cd testsuite/tests/$foo; make
because the latter will not set TERM=dumb and toplevel tests will use
nice escape-code location highlighting instead of ASCII-made squiggly
lines, which breaks the tests.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15716 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
update Changes after cherry-picking from trunk to 4.02

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15717 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02