With respect to the change in awk's behavior I reported:

I've heard back from arnold at gnu.org, who confirmed that this was
intentional (but has not yet confirmed that this is a POSIX 
compliance issue -- rather just that this is a change in a boundary
condition).  Several people have suggested simple changes to 
my scripts -- if I only had a few, I would do so, but it ain't
that easy at the moment.

Arnold also asked that I point out that gawk is now up to version
3.0.3, said that 2.15.6 is quite out of date, and suggested that 
I update.  Since it looks as if I will have to maintain a custom 
version of gawk for a while, in order to  support our scripts, I 
will investigate doing that for our systems.

He also asked me to bring the version upgrade to the attention of
the NetBSD folk.

However, I investigated the difference, and found that changing
2.15.6 to emulate 2.15.5 in this respect is very simple -- 
move a line of code back to its old location.  The patch is attached.

--- io.c        Fri Oct 13 20:16:22 1995
+++ -   Fri Jul  3 07:49:37 1998
@@ -188,14 +186,14 @@
 	cnt = get_a_record(&begin, iop, *RS, NULL);
 	if (cnt == EOF) {
 		cnt = 0;
 		retval = 1;
 	} else {
-		NR += 1;
-		FNR += 1;
-		set_record(begin, cnt, 1);
+		    NR += 1;
+		    FNR += 1;
 	}
+	set_record(begin, cnt, 1);
 
 	return retval;
 }