Avoid duplication in register names.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/abstract_intel_emit@15366 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Fix.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/abstract_intel_emit@15367 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02