Use system x265 (patch from Gentoo).
Use system libvpx (patch from FreeBSD).
Use system ffmpeg (patch from upstream).
Add fdk_acc build option (off).
Close#3987.
"The licenses of libfaac and libfdk_aac are not compatible with the GPL,
so the GPL does not permit distribution of binaries containing code
licensed under these licenses when GPL-licensed code is also included.
Therefore these encoders have been designated as "non-free", and you
cannot download a pre-built ffmpeg that supports them. This can be
resolved by compiling ffmpeg yourself."
See https://trac.ffmpeg.org/wiki/Encode/AAC.
"The licenses of libfaac and libfdk_aac are not compatible with the GPL,
so the GPL does not permit distribution of binaries containing code
licensed under these licenses when GPL-licensed code is also included.
Therefore these encoders have been designated as "non-free", and you
cannot download a pre-built ffmpeg that supports them. This can be
resolved by compiling ffmpeg yourself."
See https://trac.ffmpeg.org/wiki/Encode/AAC.
From /usr/share/doc/opera-stable/copyright:
> Subject to the terms and conditions of these Terms, Opera hereby grants
> you a limited, non-exclusive, non-transferable, non-sublicensable
> license;
> [ ... ]
> (ii) to reproduce and distribute the Software without
> modification, provided that any such reproduction or distribution of
> the Software by you: (a) must be in an application repository for a
> desktop Open Source OS distribution (expressly excluding distribution
> for embedded Open Source OS); (b) must be made available free of charge
> for end-users; (c) must be subject to and distributed with a copy of
> this Agreement; and (d) no automatic modification of the default search
> engines in the Software settings is done at any time, including but not
> limited to after the Software is installed.
