c++ PATCH: vbase dtors called multiple times

[Mark Mitchell]

Scott --

  Your patch is obviously correct.   I will commit it.

  Thank you for tracking down this bug.  I introduced this mistake
when I revamped this stuff recently, and unfortunately got this case
wrong.

  Thanks,

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