Ports: Remove some config.sub patches and download a fresh one if needed

All of these patches did the same thing, which is already in upstream
config.sub.
With this change, we need only add `use_fresh_config_sub=true` to
the package.sh file.
Note that this is not done automatically in case the port has a modified
config.sub file.

Ports/libxml2/package.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env -S bash ../.port_include.sh
 port=libxml2
 useconfigure="true"
+use_fresh_config_sub="true"
 version="2.9.12"
 files="ftp://xmlsoft.org/libxml2/libxml2-${version}.tar.gz libxml2-${version}.tar.gz c8d6681e38c56f172892c85ddc0852e1fd4b53b4209e7f4ebf17f7e2eae71d92"
 auth_type=sha256

Ports/libxml2/patches/config.sub.patch

@@ -1,11 +0,0 @@
---- libxml2-2.9.12/config.sub	2021-05-13 20:54:55.000000000 +0200
-+++ libxml2-2.9.12-patched/config.sub	2021-06-04 14:55:35.184278060 +0200
-@@ -1360,7 +1360,7 @@
- 	     | powermax* | dnix* | nx6 | nx7 | sei* | dragonfly* \
- 	     | skyos* | haiku* | rdos* | toppers* | drops* | es* \
- 	     | onefs* | tirtos* | phoenix* | fuchsia* | redox* | bme* \
--	     | midnightbsd*)
-+	     | midnightbsd* | serenity*)
- 	# Remember, each alternative MUST END IN *, to match a version number.
- 		;;
- 	qnx*)