dbus-portal: Fix return value type of filtered NameHasOwner
dbus-portal: Fix return value type of filtered NameHasOwner

Fixes https://github.com/flatpak/flatpak/issues/817

flatpak/flatpak,GeorgesStavracas/flatpak,GeorgesStavracas/flatpak,GeorgesStavracas/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,GeorgesStavracas/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,flatpak/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak