HDHomeRun Add message when signal lock status changes

Add a log message when the signal is locked or when the lock is lost.
This message is also given in the dvbsignalmonitor.

mythtv/libs/libmythtv/recorders/hdhrsignalmonitor.cpp

@@ -139,15 +139,24 @@ void HDHRSignalMonitor::UpdateValues(void)
             .arg(sig).arg(snq).arg(seq));
 
     // Set SignalMonitorValues from info from card.
+    bool wasLocked = false;
     bool isLocked = false;
     {
         QMutexLocker locker(&m_statusLock);
         m_signalStrength.SetValue(sig);
         m_signalToNoise.SetValue(snq);
+        wasLocked = m_signalLock.IsGood();
         m_signalLock.SetValue(static_cast<int>(status.lock_supported));
         isLocked = m_signalLock.IsGood();
     }
 
+    // Signal lock change
+    if (wasLocked != isLocked)
+    {
+        LOG(VB_CHANNEL, LOG_INFO, LOC + "UpdateValues -- Signal " +
+                (isLocked ? "Locked" : "Lost"));
+    }
+
     EmitStatus();
     if (IsAllGood())
         SendMessageAllGood();