The drawvg filter can draw vector graphics on top of a video, using libcairo. It
is enabled if FFmpeg is configured with `--enable-cairo`.
The language for drawvg scripts is documented in `doc/drawvg-reference.texi`.
There are two new tests:
- `fate-filter-drawvg-interpreter` launch a script with most commands, and
verify which libcairo functions are executed.
- `fate-filter-drawvg-video` render a very simple image, just to verify that
libcairo is working as expected.
Signed-off-by: Ayose <ayosec@gmail.com>
