This patch moves FFMPEG building to buildbots:
- `ffmpeg-mac.zip` is built on Mac 10.14 machine
- `ffmpeg-win32.zip` and `ffmpeg-win64.zip` are cross-compiled on
Ubuntu 20.04 machine
All builds across the platforms share the same config:
- the same versions of `ffmpeg` and `libvpx`
- the same build configuration for both `ffmpeg` and `libvpx`
The config could be found in the `//browser_patches/ffmpeg/CONFIG.sh`.
The builds will be then copied manually and committed to the git
repository.
This establishes a single naming for all our blobs with browser
builds that we upload to CDN: `<browser-name>-<os-version>`
- `<browser-name>` is either `firefox` or `webkit`.
- `os-version` is the OS that was used to produce the build.
References #2745
This patch establishes the following convention:
- scripts `checkout_build_archive_upload.sh` and `upload.sh` now accept
build flavor instead of browser name. Build flavor fully defines the
build produced / uploaded.
- scripts under `//browser_patches/webkit` and
`//browser_patches/firefox` produce build that is specific to the host
system.
