Add dev-qt from an older version of the gentoo repo

Qt5 has been removed, we restore it since we still use it.

dev-qt/qtgraphicaleffects/Manifest

@@ -0,0 +1 @@
+DIST qtgraphicaleffects-everywhere-opensource-src-5.15.18.tar.xz 14021560 BLAKE2B 20c197be8ef578bc06bbf229daa0f62061f379728a064acf18d447e51df5f4e51d06d9a61f00ac7c39a582c906a1874576f8f3787595f7fe0cfb90a190e2d12e SHA512 6fff9181d8d0a4f55987e2b219d35adf4db28429206e4ec0572a03664c155aea046a08a1d820fbc5d27f9f3ec4c60768823959c5839766ab2768f64c440273da

dev-qt/qtgraphicaleffects/metadata.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="project">
+		<email>qt@gentoo.org</email>
+		<name>Gentoo Qt Project</name>
+	</maintainer>
+	<upstream>
+		<bugs-to>https://qt-project.atlassian.net/</bugs-to>
+		<doc>https://doc.qt.io/</doc>
+	</upstream>
+	<slots>
+		<subslots>
+			Must only be used by packages that are known to use private parts of the Qt API.
+		</subslots>
+	</slots>
+</pkgmetadata>

dev-qt/qtgraphicaleffects/qtgraphicaleffects-5.15.18.ebuild

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+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+VIRTUALX_REQUIRED="test"
+inherit qt5-build
+
+DESCRIPTION="Set of QML types for adding visual effects to user interfaces"
+
+if [[ ${QT5_BUILD_TYPE} == release ]]; then
+	KEYWORDS="amd64 ~arm arm64 ~hppa ~loong ppc ppc64 ~riscv x86"
+fi
+
+IUSE=""
+
+RDEPEND="
+	=dev-qt/qtcore-${QT5_PV}*
+	=dev-qt/qtdeclarative-${QT5_PV}*
+	=dev-qt/qtgui-${QT5_PV}*
+"
+DEPEND="${RDEPEND}"