Have GW take joystick as input

[BrianPugh]

Currently, all other emu's use the joystick abstraction as an input; GW does not. This leads to a small bug where when macros are used, the underlying keypresses are still being sent to the emulator because GW directly reads buttons.

[bzhxx]

we can change it in main_gw.c.

game-and-watch-retro-go/Core/Src/porting/gw/main_gw.c

Line 53 in 1bc9ff8

/* callback to get buttons state */

.
The emulator is calling gw_get_buttons() everytime the rom program reads inputs.
We just need to replace buttons_get() by an operation to convert joystick state in original buttons value.