eventdemo: use zalloc

Zero-initialize the struct, just in case.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Yong Bakos <ybakos@humanoriented.com>
Tested-by: Yong Bakos <ybakos@humanoriented.com>
Reviewed-by: Benoit Gschwind <gschwind@gnu-log.net>
Tested-by: Benoit Gschwind <gschwind@gnu-log.net>

clients/eventdemo.c

@@ -373,7 +373,7 @@ eventdemo_create(struct display *d)
 {
 	struct eventdemo *e;
 
-	e = malloc(sizeof (struct eventdemo));
+	e = zalloc(sizeof (struct eventdemo));
 	if (e == NULL)
 		return NULL;