Leverage go-kdfs [1] to automatically generate tables (basic info
for single-plane formats, YUV list, opaque list). This allows us
to drop our manually written tables and check format info in a kdfs
viewer (the kdfs CLI or pixfmtdb) to ensure it's correct.
Add a new gen-pixel-format ninja target to regenerate tables. Tables
are checked in Git instead of being generated at build-time, so
that the kdfs CLI isn't a build-time dependency.
block_width/block_height are now never zero.
[1]: https://gitlab.freedesktop.org/emersion/go-kdf
