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/grep/package.sh

@@ -6,6 +6,7 @@ https://ftpmirror.gnu.org/gnu/grep/grep-${version}.tar.gz.sig grep-${version}.ta
 https://ftpmirror.gnu.org/gnu/gnu-keyring.gpg gnu-keyring.gpg"
 
 useconfigure=true
+use_fresh_config_sub=true
 configopts=("--disable-perl-regexp")
 auth_type="sig"
 auth_opts=("--keyring" "./gnu-keyring.gpg" "grep-${version}.tar.gz.sig")

Ports/grep/patches/fix-autoconf.patch

@@ -1,10 +0,0 @@
---- grep-2.5.4/config.sub.orig	Sat Jan 25 11:56:17 2020
-+++ grep-2.5.4/config.sub	Sat Jan 25 11:56:28 2020
-@@ -1204,6 +1204,7 @@
- 	# 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* | -sunos | -sunos[34]*\
- 	      | -hpux* | -unos* | -osf* | -luna* | -dgux* | -solaris* | -sym* \
- 	      | -amigaos* | -amigados* | -msdos* | -newsos* | -unicos* | -aof* \