## Description
A few improvements to the ffmpeg decoder & mpv build scripts. Mainly
changes the dependency fetching so the scripts are more idempotent,
though some rebuilds still always occur.
### Related issues
Related to
https://github.com/damontecres/Wholphin/pull/1106#issuecomment-4077678690
### Testing
Local builds
## Screenshots
N/A
## AI or LLM usage
None
Experimental MPV player backend
Related to #14, #22, & #85
You can switch to MPV in advanced settings and toggle using hardware
decoding or not.
This uses code and buildscripts from
https://github.com/mpv-android/mpv-android, plus other third party
libraries to build MPV
