Re: bin/58115: [RB] usr.bin/config: stabilize ioconf.c output

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

We should just use mergesort(3) in config(1).  However, that requires
adding it to tools/compat, which is a bit of rigmarole judging by the
heapsort(3) we already have there, so it's not trivial.

Maybe we could do it more easily by just replacing heapsort by
mergesort in the tools build anyway.  None of this is a bottleneck,
and the memory savings of heapsort is just as insignificant as the
(potential) performance benefit of qsort.