xwayland: Check zalloc return for out of memory situation

Signed-off-by: Bryce Harrington <b.harrington@samsung.com>
diff --git a/xwayland/launcher.c b/xwayland/launcher.c
index ac692de..70703a4 100644
--- a/xwayland/launcher.c
+++ b/xwayland/launcher.c
@@ -348,6 +348,8 @@
 	char lockfile[256], display_name[8];
 
 	wxs = zalloc(sizeof *wxs);
+	if (wxs == NULL)
+		return -1;
 	wxs->process.cleanup = weston_xserver_cleanup;
 	wxs->wl_display = display;
 	wxs->compositor = compositor;