Ports: Add GNU sed 4.2.1 (#1127)

4.2.1 was the last version not to depend upon Gnulib.

Ports/sed/package.sh

@@ -0,0 +1,5 @@
+#!/bin/bash ../.port_include.sh
+port=sed
+version=4.2.1
+useconfigure="true"
+files="https://ftp.gnu.org/gnu/sed/sed-4.2.1.tar.bz2 sed-4.2.1.tar.bz2"

Ports/sed/patches/config.sub.patch

@@ -0,0 +1,11 @@
+--- ./build-aux/config.sub	2009-06-15 10:05:11.000000000 +0100
++++ ./build-aux/config.sub.sos	2020-01-24 10:43:44.561780477 +0000
+@@ -1269,7 +1269,7 @@
+ 	-gnu* | -bsd* | -mach* | -minix* | -genix* | -ultrix* | -irix* \
+ 	      | -*vms* | -sco* | -esix* | -isc* | -aix* | -cnk* | -sunos | -sunos[34]*\
+ 	      | -hpux* | -unos* | -osf* | -luna* | -dgux* | -solaris* | -sym* \
+-	      | -kopensolaris* \
++	      | -kopensolaris* | -serenity* \
+ 	      | -amigaos* | -amigados* | -msdos* | -newsos* | -unicos* | -aof* \
+ 	      | -aos* | -aros* \
+ 	      | -nindy* | -vxsim* | -vxworks* | -ebmon* | -hms* | -mvs* \