_mcd_account_get_avatar: don't segfault on NULL out-parameters
_mcd_account_get_avatar: don't segfault on NULL out-parameters

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control