Only display heat results if DISPLAY is set

examples/heat/heat.c

@@ -804,7 +804,8 @@ int main(int argc, char **argv)
 	}
 
 #ifdef STARPU_OPENGL_RENDER
-	opengl_render(ntheta, nthick, result, pmesh, argc, argv);
+	if (getenv("DISPLAY"))
+		opengl_render(ntheta, nthick, result, pmesh, argc, argv);
 #endif
 
 	free(pmesh);