Hints for libretro-mgba in main

Warnings

• asv-cid-is-not-rdns
  :3 - libretro-mgba
  The component ID is required to follow a reverse domain-name scheme for its name. See the AppStream specification for details.
• internal-unknown-tag
  The generator emitted a tag 'internal-unknown-tag' which is unknown. This is a bug in the metadata generator, please file a bugreport.