build: Enable xwayland-test during distcheck

The replacement xwayland-test should succeed, so we should run it
from distcheck again.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
diff --git a/Makefile.am b/Makefile.am
index 589b47b..1864b70 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -8,8 +8,7 @@
 noinst_LTLIBRARIES =
 BUILT_SOURCES =
 
-# Do not run xwayland test while it is known broken.
-AM_DISTCHECK_CONFIGURE_FLAGS = --disable-setuid-install --disable-xwayland-test
+AM_DISTCHECK_CONFIGURE_FLAGS = --disable-setuid-install
 
 EXTRA_DIST = weston.ini.in ivi-shell/weston.ini.in