Add compatibility with FFMPEG 7.0

[eclipseo]

channel_layout has been replaced with ch_layout

Fix: #16437

[LibretroAdmin]

I have asked @hizzlekizzle to test this. Thanks for doing this.

[hizzlekizzle]

@LibretroAdmin just got done testing and all seems well. It does what it says on the tin.

[eclipseo]

@LibretroAdmin just got done testing and all seems well. It does what it says on the tin.

Simplified the code following feedback from another patch from another project.

[LibretroAdmin]

Confirmed with @hizzlekizzle that the latest patch worked for him.

Thanks so much for this. This will make ffmpeg viable again on Linux.

[nunotexbsd]

@LibretroAdmin

Hello

1.21.0 fails to build with FFmpeg 8, should I open a new PR?

<snip>
record/drivers/record_ffmpeg.c:377:25: error: use of undeclared identifier 'AV_INPUT_BUFFER_MIN_SIZE'
  377 |    audio->outbuf_size = AV_INPUT_BUFFER_MIN_SIZE;
      |                         ^
record/drivers/record_ffmpeg.c:954:7: warning: call to undeclared function 'avcodec_close'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  954 |       avcodec_close(handle->audio.codec);
      |       ^
record/drivers/record_ffmpeg.c:962:7: warning: call to undeclared function 'avcodec_close'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  962 |       avcodec_close(handle->video.codec);
      |       ^
2 warnings and 1 error generated.

Thanks