sys-devel/m4: Sync with Gentoo

It's from Gentoo commit 4fed18359c68f6071acb04851e80ba1a23ea6c72.

Signed-off-by: Flatcar Buildbot <buildbot@flatcar-linux.org>

sdk_container/src/third_party/portage-stable/sys-devel/m4/Manifest

@@ -3,3 +3,5 @@ DIST m4-1.4.19.tar.xz 1654908 BLAKE2B 08694485a49c542761fa9a7db4d7609f4dfb08a5c6
 DIST m4-1.4.19.tar.xz.sig 488 BLAKE2B 99e89b1ed0bf158d29a652392fb122e23227e895c75a8c63057ebe33f11b433ab205ae99a991578a89df8c3e723fc00669d8cdb290fbc86eaa6c704b112e4370 SHA512 d6ac9c6a54c57e9b53fb3e34a60d49df2f46a6e494da0a0c9ae8246b984e68a853b5d8c42677c1a0485c3f36b0bce10a481d3775c0edc1dbdfb27b43545bc31e
 DIST m4-1.4.20.tar.xz 2044756 BLAKE2B d8e6716dd4f35e17b866917f0697f980d7b6fbfa9aa92feb1234fdb49fb62107dc48405036a8ca97db73889d7638b90b69ea005352992b7bf45e8605127b318f SHA512 dc7b4f61452e564b095010029bf6ce4246e5a03959989cd76b09eb8012db7424c52819143020fab21a3471ff57ab026d3eccbd00dd3969819208980565a9fec0
 DIST m4-1.4.20.tar.xz.sig 488 BLAKE2B a202c6d8f7d65bf8f4936ec5d18bce768fe80ab485905cce051339fffdecbdd191f73b25675770648536ee24c2b161416e924b6acd30c1d8d00a425174f0a439 SHA512 bc75a64e47a87fe4073f26850a8344e82d15f156ac5b52cde1af701a0ba4e0d18f414323f86c868f114c4867b00c31ce205a9505343e588ad97825b05136c5eb
+DIST m4-1.4.21.tar.xz 2080016 BLAKE2B 047573505e04295ba94e7b3eff6c705d7e7b8ed9e7794a686b04a709acb2f3edaea54eb0e76b7f9ffeb1b3dc48e9e34ad8d7b73633e7a1fca4348b13b4b5cc28 SHA512 efe5ec212f6431129a79667f098b2efe2e824122112f73a675deccb9c0d8c9b0bc9e3bf50c9cd5c0b894dc0af1b3f02253e5e67893fb9548a6a9d3bed7c829f7
+DIST m4-1.4.21.tar.xz.sig 488 BLAKE2B 08ab88deccdf9e2e55b98361886042a9d61499fe26e6c1526cd1690611b91927ce626552bce30ceec18d61468eb94bafc1f52b598e7e8c89b21af6c21ed752f2 SHA512 033c1481a1629bcc6ae1cb3437630b00a6b04a4f1aecc26db33b475aff088d50aa7dd15f053cad5a7014ce1b197e8533b8fc5f8f555a952ddb334a9d6e1af059

sdk_container/src/third_party/portage-stable/sys-devel/m4/m4-1.4.21.ebuild

@@ -0,0 +1,90 @@
+# Copyright 1999-2026 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+VERIFY_SIG_OPENPGP_KEY_PATH=/usr/share/openpgp-keys/m4.asc
+inherit branding flag-o-matic verify-sig
+
+DESCRIPTION="GNU macro processor"
+HOMEPAGE="https://www.gnu.org/software/m4/m4.html"
+if [[ ${PV} == *_p* ]] ; then
+	# Note: could put this in devspace, but if it's gone, we don't want
+	# it in tree anyway. It's just for testing.
+	MY_SNAPSHOT="$(ver_cut 1-3).65-bdd9"
+	SRC_URI="
+		https://alpha.gnu.org/gnu/${PN}/${PN}-${MY_SNAPSHOT}.tar.xz
+		https://people.redhat.com/eblake/${PN}/${PN}-${MY_SNAPSHOT}.tar.xz
+		verify-sig? (
+			https://alpha.gnu.org/gnu/${PN}/${PN}-${MY_SNAPSHOT}.tar.xz.sig
+			https://people.redhat.com/eblake/${PN}/${PN}-${MY_SNAPSHOT}.tar.xz.sig
+		)
+	"
+	S="${WORKDIR}"/${PN}-${MY_SNAPSHOT}
+else
+	SRC_URI="mirror://gnu/${PN}/${P}.tar.xz"
+	SRC_URI+=" verify-sig? ( mirror://gnu/${PN}/${P}.tar.xz.sig )"
+	KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~loong ~m68k ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86 ~arm64-macos ~x64-macos ~x64-solaris"
+fi
+
+LICENSE="GPL-3+"
+SLOT="0"
+IUSE="examples nls"
+
+RDEPEND="
+	virtual/libiconv
+	nls? (
+		sys-devel/gettext
+		virtual/libintl
+	)
+"
+DEPEND="${RDEPEND}"
+# Remember: cannot dep on autoconf since it needs us
+BDEPEND="
+	app-arch/xz-utils
+	nls? ( sys-devel/gettext )
+	verify-sig? ( sec-keys/openpgp-keys-m4 )
+"
+
+src_prepare() {
+	default
+
+	# touch generated files after patching m4, to avoid activating maintainer
+	# mode
+	# remove when loong-fix-build.patch is no longer necessary
+	#touch ./aclocal.m4 ./lib/config.hin ./configure ./doc/stamp-vti || die
+	#find . -name Makefile.in -exec touch {} + || die
+}
+
+src_configure() {
+	# see https://bugs.gentoo.org/955947
+	append-flags -Wno-error=format-security
+
+	local -a myeconfargs=(
+		--enable-changeword
+		$(usex nls '' '--disable-nls')
+
+		# Disable automagic dependency over libsigsegv; see bug #278026
+		ac_cv_libsigsegv=no
+	)
+
+	econf "${myeconfargs[@]}"
+}
+
+src_test() {
+	[[ -d /none ]] && die "m4 tests will fail with /none/" # bug #244396
+	emake check
+}
+
+src_install() {
+	default
+
+	# autoconf-2.60 for instance, first checks gm4, then m4.  If we don't have
+	# gm4, it might find gm4 from outside the prefix on for instance Darwin
+	use prefix && dosym m4 /usr/bin/gm4
+
+	if use examples ; then
+		dodoc -r examples
+		rm -f "${ED}"/usr/share/doc/${PF}/examples/Makefile*
+	fi
+}