Can't be booted in DSi mode on the DSpico flashcard if there's no SD card inserted in the DSi SD slot

[Dartz150]

Either standalone or by launching it as a file extension (argv), this may be related to how libnds handles the drives available, which always tries to mount the SD card while in DSi mode.

Since the DSpico loads from fat in DSi mode, this check fails if there's no card inserted in the DSi slot, and makes GBARunner3 to hang in a white screen.