Fixed VS2015 compiler error of using pointer arithmetic on void*
Fixed VS2015 compiler error of using pointer arithmetic on void*

grimfang4/sdl-gpu,grimfang4/sdl-gpu,ademuri/sdl-gpu,grimfang4/sdl-gpu,ademuri/sdl-gpu,grimfang4/sdl-gpu,ademuri/sdl-gpu,ademuri/sdl-gpu