dev-util/xxd: Add from Gentoo

It's from Gentoo commit 4d3a957c9a0dcc3e4a274c09e39c9da7a7aabfe4.

Signed-off-by: Krzesimir Nowak <knowak@microsoft.com>

sdk_container/src/third_party/portage-stable/dev-util/xxd/Manifest

@@ -0,0 +1 @@
+DIST vim-9.1.1683.tar.gz 18762645 BLAKE2B e43f060668131fbf84cdaf7c8f831787f9a3e46607c8af8b67b78490abfcc9c2ab277ea53ddbedf7bee899034b06278cf1d67ddd9d397272ef9d97d909d3fafd SHA512 1d68f55198bb363933e04e925118b6d03ddf775f35e67d7a41464df1ae86a0f2efff7434a0a169e89b1453b554c00b6bfc0dfe3b0b0a8651e4ac89267bc51316

sdk_container/src/third_party/portage-stable/dev-util/xxd/files/xxd-completion

@@ -0,0 +1,24 @@
+# Author: Ciaran McCreesh <ciaranm@gentoo.org>
+#
+# completion for xxd
+
+_xxd()
+{
+    local cur prev cmd args
+
+    COMPREPLY=()
+    cur=${COMP_WORDS[COMP_CWORD]}
+    prev=${COMP_WORDS[COMP_CWORD-1]}
+    cmd=${COMP_WORDS[0]}
+
+    if [[ "${cur}" == -* ]] ; then
+        args='-a -b -c -E -g -h -i -l -ps -r -s -u -v'
+        COMPREPLY=( $( compgen -W "${args}" -- $cur ) )
+    else
+        _filedir
+    fi
+}
+
+complete -F _xxd xxd
+
+# vim: set ft=sh sw=4 et sts=4 :

sdk_container/src/third_party/portage-stable/dev-util/xxd/metadata.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="person" proxied="yes">
+		<email>holger@applied-asynchrony.com</email>
+		<name>Holger Hoffstätte</name>
+	</maintainer>
+	<maintainer type="project" proxied="proxy">
+		<email>proxy-maint@gentoo.org</email>
+		<name>Proxy Maintainers</name>
+	</maintainer>
+	<upstream>
+		<remote-id type="github">vim/vim</remote-id>
+		<remote-id type="cpe">cpe:/a:vim:vim</remote-id>
+	</upstream>
+</pkgmetadata>

sdk_container/src/third_party/portage-stable/dev-util/xxd/xxd-2025.08.24-r1.ebuild

@@ -0,0 +1,49 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit bash-completion-r1 toolchain-funcs
+
+VIM_VERSION="9.1.1683"
+
+DESCRIPTION="Standalone version of Vim's xxd"
+HOMEPAGE="
+	https://www.vim.org
+	https://github.com/vim/vim
+"
+SRC_URI="https://github.com/vim/vim/archive/v${VIM_VERSION}.tar.gz -> vim-${VIM_VERSION}.tar.gz"
+
+S="${WORKDIR}/vim-${VIM_VERSION}/src/xxd"
+LICENSE="|| ( GPL-2 MIT )"
+SLOT="0"
+
+KEYWORDS="~alpha amd64 arm arm64 ~hppa ~loong ~m68k ~mips ppc ppc64 ~riscv ~s390 ~sparc x86 ~arm64-macos ~x64-macos ~x64-solaris"
+
+RDEPEND="!<app-editors/vim-core-9.1.1652-r1"
+
+src_prepare() {
+	default
+
+	# international man pages need some renaming:
+	# xxd-<lang>.UTF-8.1 -> xxd.<lang>.1
+	cd ../../runtime/doc || die
+	local f newname
+	for f in xxd-*.UTF-8.1 ; do
+		newname=${f//xxd-/xxd.}
+		newname=${newname//UTF-8\./}
+		mv -f "${f}" "${newname}" || die
+	done
+}
+
+src_compile() {
+	tc-export CC
+	export {C,CPP,LD}FLAGS
+	emake
+}
+
+src_install() {
+	dobin xxd
+	doman ../../runtime/doc/xxd*.1
+	newbashcomp "${FILESDIR}"/xxd-completion xxd
+}