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/libjpeg/package.sh

@@ -2,6 +2,7 @@
 port=libjpeg
 version=9d
 useconfigure=true
+use_fresh_config_sub=true
 files="https://ijg.org/files/jpegsrc.v${version}.tar.gz jpeg-${version}.tar.gz 2303a6acfb6cc533e0e86e8a9d29f7e6079e118b9de3f96e07a71a11c082fa6a"
 auth_type=sha256
 workdir="jpeg-$version"

Ports/libjpeg/patches/system-detect.patch

@@ -1,11 +0,0 @@
---- jpeg-9d/config.sub.orig	2021-02-17 23:18:21.463855433 +0000
-+++ jpeg-9d/config.sub	2021-02-17 23:18:42.043804955 +0000
-@@ -1390,7 +1390,7 @@
- 	      | -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*)