screenshooter: silence a warning

screenshooter.c: In function ‘recorder_binding’:
screenshooter.c:509:5: warning: ‘listener’ may be used uninitialized in
this function [-Wuninitialized]

This was not really a problem so far, because the variable was
uninitialized only in the case where Weston had no outputs.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

src/screenshooter.c

@@ -495,7 +495,7 @@ recorder_binding(struct weston_seat *seat, uint32_t time, uint32_t key, void *da
 	struct weston_seat *ws = (struct weston_seat *) seat;
 	struct weston_compositor *ec = ws->compositor;
 	struct weston_output *output;
-	struct wl_listener *listener;
+	struct wl_listener *listener = NULL;
 	struct weston_recorder *recorder;
 	static const char filename[] = "capture.wcap";