[RFC PATCH 1/2] Add a scoped warning disabler.

[Jason Riedy]

And John W. Eaton writes:
> Any change like this will have to wait until after 3.0.

No hurries.  This is just to support a sparse->dense warning that
I'm going to use personally.  I'll at least get some warning
before I nuke the IA64 nodes here.  You can densify a huge matrix
accidentally...

> Can you please explain what this does/how it is used?

In the next patch, sparse.cc(Ffull) will have
DEFUN_DLD (full, ...)
{
  const octave_warning_suspend densifies("Octave:unexpectedly-densifying");
...
}

Then the warning is disabled on entry (if enabled) and reset to
the entry state on exit.

Oh, hell.  I sent a bogus 2/2 patch.

Jason