Re: Fix NULL pointer reference in _outPathTarget()

A semantics-preserving conversion would have looked something like

    if (node->sortgrouprefs)
        WRITE_INDEX_ARRAY(sortgrouprefs, list_length(node->exprs));

I suppose that Peter was trying to remove special cases from the
outfuncs.c code, but do we want to put this one back?  Richard's
proposal would not accurately reflect the contents of the data
structure, so I'm not too thrilled with it.

"
This also changes the behavior slightly: Before, the field name was
skipped if the length was zero.  Now it prints the field name even in
that case.  This is more consistent with how other array fields are
handled.
"

So I suppose we are trying to print the field name even if the length is
zero. Should we keep this behavior in the fix?

Thanks
Richard