AmberELEC and ROCKNIX install a retroarch.cfg whose system_directory
points every core at the BIOS folder. retroarch.yml (type utility, no
file, no system) reads that key, and ROCKNIX's systemfiles_in_content_dir,
at the RetroArch each one compiles: v1.22.2 and bdba046f. all_libretro
never picks a utility profile, and lists naming retroarch gain no file.
A libretro core option a frontend record writes stays the core's to
read: RetroDECK's pcsx2_bios keeps lrps2 as its reader.