initialization of Uint8 in SDLInput.cpp

[interkosmos]

Compiling Sources/Engine/Base/SDL/SDLInput.cpp failes with:

/tmp/Serious-Engine-master/Sources/Engine/Base/SDL/SDLInput.cpp:727:12: error: cannot initialize a variable of type 'Uint8 *' (aka 'unsigned char *') with an rvalue of type 'const Uint8 *' (aka 'const unsigned char *')
    Uint8 *keystate = SDL_GetKeyboardState(NULL);

The declaration must be changed to:

    const Uint8 *keystate = SDL_GetKeyboardState(NULL);