win: Don't call ecore_x_screensaver APIs if elm win doesn't have X11 window

win: Don't call ecore_x_screensaver APIs if elm win doesn't have X11 window

Summary:
Elementary application crashes on startup when it is running with
wayland engine. This crash problem happens while ecore_x_screensaver API
is being called from _win_noblank_eval funcion. Thus we should not call
ecore_x_screensaver APIs if elm win doesn't have X11 window.

Test Plan:
1. build efl and elementary to support x11 and also wayland
1. run weston without xwayland
2. run elementary_test on the weston

Reviewers: raster, seoz, stefan_schmidt, devilhorns

Differential Revision: https://phab.enlightenment.org/D1293