package/libvpx: bump version to 1.7.0
Switched _SITE to github, current _SITE is broken.
The URL
https://chromium.googlesource.com/webm/libvpx/+archive/v1.7.0.tar.gz
proposed by upstream
https://storage.googleapis.com/downloads.webmproject.org/releases/webm/index.html
provides archives with different hashes for each download so we use
Github instead.
Added license hashes.
Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>