chromecast: initialize i_requestId

This fix the random start fail of the module.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/stream_out/chromecast/cast.cpp

@@ -73,7 +73,8 @@ enum
 struct sout_stream_sys_t
 {
     sout_stream_sys_t()
-        : p_tls(NULL), i_status(CHROMECAST_DISCONNECTED), p_out(NULL)
+        : p_tls(NULL), i_requestId(0),
+          i_status(CHROMECAST_DISCONNECTED), p_out(NULL)
     {
         atomic_init(&ab_error, false);
     }