fix SteadyClock vs Systemclock issues

src/zm_monitor.h

@@ -534,6 +534,9 @@ public:
       return shared_data->last_viewed_time;
     return 0;
   }
+  void setLastViewed() {
+    setLastViewed(std::chrono::system_clock::now());
+  }
   void setLastViewed(SystemTimePoint new_time) {
     if (shared_data && shared_data->valid)
       shared_data->last_viewed_time = 

src/zm_monitorstream.cpp

@@ -582,7 +582,7 @@ void MonitorStream::runStream() {
     }
 
     now = std::chrono::steady_clock::now();
-    monitor->setLastViewed(now);
+    monitor->setLastViewed();
 
     bool was_paused = paused;
     bool got_command = false; // commands like zoom should output a frame even if paused