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[sakgoyal]

#536

[sakgoyal]

instead of using the generate_ffi.sh script, use the bindgen cli to directly generate it. this makes the generation cross platform (with workarounds for pkgconfig on windows) .

it also makes sure it stays in sync with the OS (windows/unix generate different bindings).

this also removes the need for separate ffi_ffmpeg-xxxx.rs. it will automatically generate the file depending on the installed version.

[sakgoyal]

for now it assumes it's installed in c:/ffmpeg on windows. you could probably change it. but I don't want to deal with searching for that file.

[sakgoyal]

@izderadicka can you review this please?