Revert "avcodec: allow compilation with lavc 55"

This reverts commit 184e8e76c475c19d1626e6c2d90460e8b1fa9e6c.
Revert "avcodec: replace gone CODEC_ID_* with AV_CODEC_ID_*"

This reverts commit 7a4eb7be29852bedf50a15e7fa4f326c44b7a83b.
Revert "avcodec: remove support for old versions"

This reverts commit cde81e52f2d6e17383aced57fe6312eafa79cacf.
Revert "avcodec: require version 24.25.0 or later"

This reverts commit 364806defd8fe30b9e3a5fc3d62bbef58b7e5778.
omxil: Switch to the alternative OMX ABI, used on the raspberry pi

This breaks usage of the omxil decoder with any other OMX core - this
cannot easily be switched at runtime since it affects how structs
are laid out.
omxil: Try to load the broadcom host library and IL core

Don't unload the library though. On init, it starts background
threads, which keep running even after the library is deinitialized.
Therefore, this library cannot be unloaded after being loaded and
initialized.
omxil: Hardcode the fact that the OMX.broadcom.video_decode supports the role video_decoder.avc
omxil: Change the signalled OMX version to 1.1.2

The broadcom OMX IL core requires this in order to respond to
requests.

This shouldn't probably break other OMX cores, unless they are
picky about it in the same way, requiring version 1.1.1.
omxil: Use larger input buffers to the decoder

The default ones on the raspberry pi aren't large enough for higher
resolution content.