openmw: ffmpeg_3 -> ffmpeg

[peterhoeg]

Motivation for this change

#120705

Cc: @abbradar

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[r-rmcgibbo]

Result of nixpkgs-review pr 123607 at f9cdbd7b run on x86_64-linux 1

1 package failed to build:

• openmw-tes3mp

1 package skipped due to time constraints:

• tests.trivial

1 package built successfully:

• openmw

Note that build failures may predate this PR, and could be nondeterministic or hardware dependent.
Please exercise your independent judgement. Does something look off? Please file an issue or reach out on IRC.

[peterhoeg]

tes3 was fixed up as well while at it. The launcher scripts are done separately now to avoid having to rebuild everything in case of changes to either lua or launcher scripts.

[ghost]

can we change ffmpeg to ffmpeg_4 because sound files don't work when openmw is built with ffmpeg, which is version 5.1 now, my issue is well described here. I tested and building with ffmpeg_4 fixes the issue and sound works as expected in game.

[dotlambda]

@davitgog https://gitlab.com/OpenMW/openmw/-/issues/6631 was closed, maybe we just need to update openmw?

[ghost]

@dotlambda 0.48 also fixes the ffmpeg 5 issue. Already tested it.