testing/libretro-bluemsx: upgrade to 0_git20240808
https://github.com/libretro/blueMSX-libretro/compare/92d0c41...824690b
Fixes rebuild errors with gcc 14.
https://github.com/libretro/blueMSX-libretro/compare/92d0c41...824690b
Fixes rebuild errors with gcc 14.