installable_cores removed every buildbot name the image builds, so a
libretro core sharing its name with a standalone package was lost:
Batocera runs amiberry standalone and its x86_64 boards fetch
amiberry_libretro. A name now compares within its build mode, and the
resolver and the layouts treat such a core as the emulator's libretro
build, run both ways. Batocera gains amiberry, azahar, cannonball, cemu,
dosbox, ecwolf, eduke32, fsuae, openmsx, rpcs3, supermodel, vita3k, xemu
and ymir as installable, KNULLI cannonball.