Ports: Replace mc config.sub patch with our own download

`mc` runs `autoconf` on the fly, which unpacks a `config.sub` from its
own files. This means that support for `serenity` (and the fact whether
the patch successfully applies) depends on the version of `autoconf`
that is installed on the host.

Instead, just always replace it with a fresh version straight from the
GNU server.

Ports/mc/patches/0002-filemanager-ext.c-Include-strings.h-if-SerenityOS.patch

@@ -1,30 +0,0 @@
-From 749c81e5006dea41daf16e99c8a60926236d2373 Mon Sep 17 00:00:00 2001
-From: Kenneth Myhra <kennethmyhra@gmail.com>
-Date: Sat, 25 Dec 2021 19:15:35 +0100
-Subject: [PATCH 2/3] filemanager/ext.c: Include strings.h if SerenityOS
-
-- [ ] Local?
-- [X] Should be merged to upstream?
-- [ ] Resolves issue(s) with our side of things
-- [ ] Hack
----
- src/filemanager/ext.c | 3 +++
- 1 file changed, 3 insertions(+)
-
-diff --git a/src/filemanager/ext.c b/src/filemanager/ext.c
-index 781a763..33baf8c 100644
---- a/src/filemanager/ext.c
-+++ b/src/filemanager/ext.c
-@@ -36,6 +36,9 @@
- #include <stdlib.h>
- #include <stdio.h>
- #include <string.h>
-+#ifdef __serenity__
-+#include <strings.h>
-+#endif
- #include <unistd.h>
- 
- #include "lib/global.h"
--- 
-2.25.1
-