L-trigger mapping

Some parts of the code might require the pressing of the L-trigger for testing reasons.

If you need that, alter controller_sdl.c. In the following line:

    if (SDL_GameControllerGetButton(sdl_cntrl, SDL_CONTROLLER_BUTTON_LEFTSHOULDER))    pad->button |= Z_TRIG;

Replace Z_TRIG with L_TRIG, save and rebuild.

On a DS4, this now means that Z-trigger will be mapped to L2 and the L-trigger to L1.