Add support for some arcade bootlegs using genesis hardware

[arcadez2003]

Aladdin, Bare Knuckle 2 + 3 and Sonic The Hedgehog 2

Not enabled in the build as yet.

[arcadez2003]

@amadvance looking at the errors it's related to handlers i've already declared in genesis.h

extern int genesis_region;
extern READ16_HANDLER ( genesis_68000_io_r );
extern WRITE16_HANDLER ( genesis_68000_io_w );

Im pretty confident if you merge the pr's everything should end up fine and dandy, all i need to
do is to enable the new romsets and declare them in mamedriv.c which will then throw up some
more temp errors :)