Ports: Add libksba port

Author: https://github.com/gunnarbeutner
Commit: https://github.com/SerenityOS/serenity/commit/700cad45082
Pull-request: https://github.com/SerenityOS/serenity/pull/6307
Reviewed-by: https://github.com/awesomekling

Ports/AvailablePorts.md

@@ -45,6 +45,7 @@ Please make sure to keep this list up to date when adding and updating ports. :^
 | [`libexpat`](libexpat/)        | Expat                                         | 2.2.9             | https://libexpat.github.io/                           |
 | [`libffi`](libffi/)            | libffi                                        | 3.3               | https://www.sourceware.org/libffi/                    |
 | [`libiconv`](libiconv/)        | GNU libiconv                                  | 1.16              | https://www.gnu.org/software/libiconv/                |
+| [`libksba`](libksba/)          | libksba                                       | 1.5.1             | https://gnupg.org/software/libksba/index.html         |
 | [`libjpeg`](libjpeg/)          | libjpeg                                       | 9d                | https://ijg.org/                                      |
 | [`libogg`](libogg/)            | libogg                                        | 1.3.4             | https://github.com/xiph/ogg                           |
 | [`libpng`](libpng/)            | libpng                                        | 1.6.37            | https://libpng.org/                                   |

Ports/libksba/package.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env -S bash ../.port_include.sh
+port=libksba
+version=1.5.1
+useconfigure=true
+files="https://gnupg.org/ftp/gcrypt/libksba/libksba-${version}.tar.bz2 libksba-${version}.tar.bz2"
+
+pre_configure() {
+    export ksba_cv_gcc_has_f_visibility=no
+}
+
+configure() {
+    run ./configure --host="${SERENITY_ARCH}-pc-serenity" --build="$($workdir/build-aux/config.guess)" $configopts
+}

Ports/libksba/patches/configure.patch

@@ -0,0 +1,12 @@
+diff -Naur libksba-1.5.1/build-aux/config.sub libksba-1.5.1.serenity/build-aux/config.sub
+--- libksba-1.5.1/build-aux/config.sub	2016-08-22 10:40:58.000000000 +0200
++++ libksba-1.5.1.serenity/build-aux/config.sub	2021-04-14 02:31:15.924387614 +0200
+@@ -1381,7 +1381,7 @@
+ 	# The portable systems comes first.
+ 	# 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* \
++	-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* \