Re: Increase value of OUTER_VAR

Here's a more fleshed-out version of this patch. I ran around and
fixed all the places where INNER_VAR etc. were being assigned directly to
a variable or parameter of type Index, and also grepped for 'Index.*varno'
to find suspicious declarations. (I didn't change every last instance
of the latter though; just places that could possibly be looking at
post-setrefs.c Vars.)

I concluded that we don't really need to change the type of
CurrentOfExpr.cvarno, because that's never set to a special value.

The main thing I remain concerned about is whether there are more
places like set_pathtarget_cost_width(), where we could be making
an inequality comparison on "varno" that would now be wrong.
I tried to catch this by enabling -Wsign-compare and -Wsign-conversion,
but that produced so many thousands of uninteresting warnings that
I soon gave up. I'm not sure there's any good way to catch remaining
places like that except to commit the patch and wait for trouble
reports.

So I'm inclined to propose pushing this and seeing what happens.

regards, tom lane