Add SGBC option to libretro port

[rtomasa]

Hi,

I see that support for Super Game Boy Color ROM hacks is there for quite some time but I noticed that the libretro option is missing that feature:

{ "Autodetect",       OPTION_VAL_AUTODETECT_AR },
{ "Game Boy",         OPTION_VAL_GAME_BOY_AR },
{ "Super Game Boy",   OPTION_VAL_SUPER_GAME_BOY_AR },
{ "Game Boy Color",   OPTION_VAL_GAME_BOY_COLOR_AR },
{ "Game Boy Advance", OPTION_VAL_GAME_BOY_ADVANCE_AR },

Any reason for not including the SGBC?

Best Regards