configure: fail if invoked with -param=value (instead of "-param value")

(Patch by Adrien Nader!)

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13842 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
configure: remove unused variables from case...in test.

(Patch by Adrien Nader!)

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13843 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02