cmake ALLEGRO_HAVE_GETEXECNAME examples

liballeg/allegro5 CMakeLists.txt :522

check_function_exists(getexecname ALLEGRO_HAVE_GETEXECNAME)

adventuregamestudio/ags libsrc/allegro/CMakeLists.txt :47

check_function_exists(getexecname ALLEGRO_HAVE_GETEXECNAME)