Changed CMAKE_SOURCE_DIR to CMAKE_CURRENT_SOURCE_DIR to allow this script to be included in others.
Changed CMAKE_SOURCE_DIR to CMAKE_CURRENT_SOURCE_DIR to allow this script to be included in others.

grimfang4/sdl-gpu,Helios-vmg/sdl-gpu,ademuri/sdl-gpu,masonwheeler/sdl-gpu,masonwheeler/sdl-gpu,Helios-vmg/sdl-gpu,ademuri/sdl-gpu,ademuri/sdl-gpu,grimfang4/sdl-gpu,grimfang4/sdl-gpu,Helios-vmg/sdl-gpu,grimfang4/sdl-gpu,masonwheeler/sdl-gpu,ademuri/sdl-gpu,masonwheeler/sdl-gpu,Helios-vmg/sdl-gpu