deps: patch to fix *.onion MX query on c-ares

c-ares rejects *.onion MX query but forgot to set `*bufp` to NULL. This
will occur SegmentFault when free `*bufp`.

I make this quick fix and then will make a PR for c-ares either.

PR-URL: https://github.com/nodejs/node/pull/25840
Fixes: https://github.com/nodejs/node/issues/25839
Refs: https://github.com/c-ares/c-ares/blob/955df98/ares_create_query.c#L97-L103
Refs: https://github.com/c-ares/c-ares/blob/955df98/ares_query.c#L124


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>