[PATCH roland/nptl-sh] SH: Consolidate NPTL/non versions of vfork

[Roland McGrath]

> You should be able to reuse the Alpha pt-vfork.S to get the compat symbols
> correct.  C.f. Alpha's vfork.S for which symbols to define there.

Thanks.  I've updated the roland/nptl-sh branch to do this.