fix sys-libs/libportal, add fallback to 0.3

sys-libs/libportal/libportal-0.5.ebuild

@@ -2,8 +2,9 @@
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=7
+VALA_USE_DEPEND="vapigen"
 
-inherit meson
+inherit meson vala
 
 SRC_URI="https://github.com/flatpak/${PN}/releases/download/${PV}/${P}.tar.xz"
 DESCRIPTION="Flatpak portal library"
@@ -11,18 +12,32 @@ HOMEPAGE="https://github.com/flatpak/libportal"
 
 LICENSE="LGPL-2"
 SLOT="0"
-IUSE="test"
+IUSE="test vala introspection doc"
 
-KEYWORDS="~amd64"
+KEYWORDS="~amd64 ~arm64"
 
 RDEPEND="dev-libs/glib:2"
 
-DEPEND="${RDEPEND}
-	dev-util/gtk-doc"
+DEPEND="
+	${RDEPEND}
+	doc? (
+		dev-util/gtk-doc
+		dev-util/gi-docgen
+	)
+	vala? ( $(vala_depend) )
+"
+
+src_prepare() {
+	default
+	use vala && vala_src_prepare
+}
 
 src_configure() {
 	local emesonargs=(
-		$(meson_use test build-portal-test)
+		$(meson_use vala vapi)
+		$(meson_use introspection)
+		$(meson_use test portal-tests)
+		$(meson_use doc docs)
 	)
 
 	meson_src_configure