AVRounding can't be a rustified enum

[kornelski]

The crate builds all enums as Rust enums (.rustified_enum("*")), but AVRounding is expected to be OR-ed together like AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX, which is not allowed (and UB if you tried anyway).

It could use the bitflags crate instead.

[maoyutofu]

I also encountered the same problem, but I don't know how to solve it.

[maoyutofu]

I am using it at work and hope to get help. @meh