add util function for determining presence of x11 compositor
add util function for determining presence of x11 compositor

rvandegrift/e,tasn/enlightenment,FlorentRevest/Enlightenment,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,rvandegrift/e,rvandegrift/e,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,tasn/enlightenment,tizenorg/platform.upstream.enlightenment