clients & tests: use eglGetPlatformDisplayEXT when supported

Reviewed-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
diff --git a/clients/window.c b/clients/window.c
index b84d3b2..2858281 100644
--- a/clients/window.c
+++ b/clients/window.c
@@ -5392,7 +5392,10 @@
 	EGLint api = EGL_OPENGL_API;
 #endif
 
-	d->dpy = eglGetDisplay(d->display);
+	d->dpy =
+		weston_platform_get_egl_display(EGL_PLATFORM_WAYLAND_KHR,
+						d->display, NULL);
+
 	if (!eglInitialize(d->dpy, &major, &minor)) {
 		fprintf(stderr, "failed to initialize EGL\n");
 		return -1;