libvpx security update

1.7.0-8 - Resolves: rhbz1796086, rhbz1796100, rhbz1796448, rhbz1796454 - Enable webm-io explicitly 1.7.0-7 - Fix for CVE-2019-9232, CVE-2019-9433, CVE-2019-9371, CVE-2019-2126 - Resolves: rhbz1796086, rhbz1796100, rhbz1796448, rhbz1796454 - Remove php-cli BR...