memory.c: Remove a lone #ifndef GAMEPAK_FITS_IN_RAM.
cpu_c.c: Delete. It goes counter to the purpose of the emulator.
Switch to on-demand loading and memory-mapped files where available.

GCW Zero: Report decompression progress and which files are being loaded/saved during startup and shutdown.
GCW Zero: Load entire ROMs into memory again. Dingoo A320: Keep memory-mapping files due to the device not having enough memory to hold 32 MiB ROMs in private allocations.