dev-cpp/simdutf: add 9.2.1,use-flag enable build of atomic base64 API

Bump simdutf with changes as described below.

The nodejs dependency V8 requires newer simdutf atomic base64 APIs that are
not provided by simdutf by default.

The following functions are expected:
simdutf::atomic_binary_to_base64
simdutf::atomic_base64_to_binary_safe (char and char16_t)

Simdutf provides these functions when compiled with C++20 and
-DSIMDUTF_ATOMIC_REF defined.

Gate this functionality behind a new local use flag (atomic-base64).

Signed-off-by: Mike Pagano <mpagano@gentoo.org>
Part-of: https://codeberg.org/gentoo/gentoo/pulls/1986
Merges: https://codeberg.org/gentoo/gentoo/pulls/1986
Signed-off-by: Pacho Ramos <pacho@gentoo.org>

dev-cpp/simdutf/metadata.xml

@@ -5,6 +5,9 @@
     <email>gnome@gentoo.org</email>
     <name>Gentoo GNOME Desktop</name>
   </maintainer>
+  <use>
+        <flag name="atomic-base64">Enable atomic base64 calls</flag>
+  </use>
   <upstream>
     <remote-id type="github">simdutf/simdutf</remote-id>
   </upstream>

dev-cpp/simdutf/simdutf-9.2.1.ebuild

@@ -0,0 +1,59 @@
+# Copyright 1999-2026 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+DOCS_BUILDER="doxygen"
+DOCS_DIR=""
+
+PYTHON_COMPAT=( python3_{11..14} )
+
+inherit cmake docs python-any-r1
+
+DESCRIPTION="Unicode validation and transcoding at billions of characters per second"
+HOMEPAGE="https://simdutf.github.io/simdutf/"
+SRC_URI="https://github.com/${PN}/${PN}/archive/refs/tags/v${PV}.tar.gz -> ${P}.tar.gz"
+
+LICENSE="|| ( Apache-2.0 MIT )"
+SLOT="0/34"
+KEYWORDS="~amd64 ~arm ~arm64 ~loong ~ppc ~ppc64 ~riscv ~sparc ~x86"
+IUSE="atomic-base64 test"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	virtual/libiconv
+"
+DEPEND="${RDEPEND}"
+BDEPEND="
+	${PYTHON_DEPS}
+	virtual/pkgconfig
+	doc? (
+		app-text/doxygen
+	)
+"
+
+src_configure() {
+
+	local mycmakeargs+=(
+		-DSIMDUTF_TESTS=$(usex test)
+		-DSIMDUTF_ATOMIC_BASE64_TESTS=$(usex test)
+	)
+
+	if use atomic-base64; then
+		mycmakeargs+=(
+			-DSIMDUTF_CXX_STANDARD=20
+		)
+	fi
+
+	cmake_src_configure
+}
+
+src_compile() {
+	cmake_src_compile
+	use doc && docs_compile
+}
+
+src_install() {
+	cmake_src_install
+	use doc && einstalldocs
+}