infttrace vs add_thread

[law@redhat.com]

  > > Again, since I'm no longer a GDB maintainer, I'll hold off installing the
  > > fix until approved by a GDB maintainer.
  > 
  > 
  > But you do have write after approval.  Cleanups like this are considered 
  > obvious.
OK.  I've been out of the GDB development process for a long time -- I don't
want to step on any toes.  Meaning I'll probably be a little over-conservative
about this kind of stuff.

jeff