Do not keep file name in exception, after all.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/exception_registration@14110 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Simplify common case of unit-wide errors.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/exception_registration@14111 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Switch Cmi_format.Error.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/exception_registration@14112 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Switch Ctype.Tags.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/exception_registration@14113 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Switch Typetexp.Error, Typedecl.Error, Typemod.Error, Typeclass.Error.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/exception_registration@14114 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02