update_equiv_regs() and dependency chains

[Mark Mitchell]

> Mark, this is a regression from 3.0 and egcs-1.1.x  Ok for the branch
> if all of my bootstrap+regression runs pass?

Yes, but you don't need my permission any more -- not until we get closer
to 3.1.1.

Thanks,

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com