PR#6181 and PR#6590

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15462 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
sync configure with the bdf.h objinfo change

(Patch by Christopher Zimmermann)

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15465 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
minor configure changes

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15466 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02