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/qtimageformats/qtimageformats-6.11.9999.ebuild

@@ -0,0 +1,39 @@
+# Copyright 2021-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit qt6-build
+
+DESCRIPTION="Additional format plugins for the Qt image I/O system"
+
+if [[ ${QT6_BUILD_TYPE} == release ]]; then
+	KEYWORDS="~amd64 ~arm ~arm64 ~hppa ~loong ~ppc64 ~riscv ~x86"
+fi
+
+IUSE="mng"
+
+RDEPEND="
+	~dev-qt/qtbase-${PV}:6[gui]
+	media-libs/libwebp:=
+	media-libs/tiff:=
+	mng? ( media-libs/libmng:= )
+"
+DEPEND="${RDEPEND}"
+
+CMAKE_SKIP_TESTS=(
+	# heif plugin is only for Mac, test is normally auto-skipped but may
+	# misbehave with kde-frameworks/kimageformats:6[heif] (bug #927971)
+	tst_qheif
+)
+
+src_configure() {
+	local mycmakeargs=(
+		-DQT_FEATURE_jasper=OFF
+		$(qt_feature mng)
+		-DQT_FEATURE_tiff=ON
+		-DQT_FEATURE_webp=ON
+	)
+
+	qt6-build_src_configure
+}