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/flex/package.sh

@@ -4,6 +4,7 @@ version=2.6.4
 files="https://github.com/westes/flex/releases/download/v${version}/flex-${version}.tar.gz flex-${version}.tar.gz
 https://github.com/westes/flex/releases/download/v${version}/flex-${version}.tar.gz.sig flex-${version}.tar.gz.sig"
 useconfigure=true
+use_fresh_config_sub=true
 configopts=("--disable-bootstrap")
 depends=("m4" "pcre2")
 auth_type="sig"

Ports/flex/patches/fix-autoconf.patch

@@ -1,10 +0,0 @@
---- flex-2.6.4/build-aux/config.sub.orig	Thu Jan 23 22:05:46 2020
-+++ flex-2.6.4/build-aux/config.sub	Thu Jan 23 22:05:59 2020
-@@ -1375,6 +1375,7 @@
- 	# Each alternative MUST END IN A *, to match a version number.
- 	# -sysv* is not here because it comes later, after sysvr4.
- 	-gnu* | -bsd* | -mach* | -minix* | -genix* | -ultrix* | -irix* \
-+	      | -serenity* \
- 	      | -*vms* | -sco* | -esix* | -isc* | -aix* | -cnk* | -sunos | -sunos[34]*\
- 	      | -hpux* | -unos* | -osf* | -luna* | -dgux* | -auroraux* | -solaris* \
- 	      | -sym* | -kopensolaris* | -plan9* \