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/nested-client.c b/clients/nested-client.c
index 7f237e6..96cf1c8 100644
--- a/clients/nested-client.c
+++ b/clients/nested-client.c
@@ -277,7 +277,9 @@
 	/* get globals */
 	wl_display_roundtrip(client->display);
 
-	client->egl_display = eglGetDisplay(client->display);
+	client->egl_display =
+		weston_platform_get_egl_display(EGL_PLATFORM_WAYLAND_KHR,
+						client->display, NULL);
 	if (client->egl_display == NULL)
 		return NULL;