SDL2 reports the following message when we type the "/" on br-abnt2 keyboards:
The key you just pressed is not recognized by SDL. \
To help get this fixed, please report this to the SDL mailing list \
<sdl@libsdl.org> X11 KeyCode 97 (89), X11 KeySym 0x2F (slash).
That's because the corresponding entry in the scancodes table is
marked with value SDL_SCANCODE_UNKNOWN.
This commit fixes that adding the value SDL_SCANCODE_SLASH for this entry.