Fixed compress deinitialization on startup

Fixed passing of poison pill to video compress when sender thread was
not actually started.

src/video_rxtx.cpp

@@ -112,6 +112,10 @@ video_rxtx::video_rxtx(map<string, param_u> const &params): m_port_id("default")
 
 video_rxtx::~video_rxtx() {
         join();
+        if (!m_poisoned && m_compression) {
+                send(NULL);
+                compress_pop(m_compression);
+        }
         module_done(CAST_MODULE(m_compression));
         module_done(&m_receiver_mod);
         module_done(&m_sender_mod);