Fix infinite recursion crash when editing Playback Groups

[df769dc] caused a regression where TimeStretch::Save(QString) would call
TimeStretch::Save() which would call SimpleDBStorage::Save() which then calls
TimeStretch::Save(QString) causing an infinite loop.

This just makes sure we call the correct Save() method in
TimeStretch::Save(QString) to break the loop. Fixes #11492.

mythtv/libs/libmythtv/playgroup.cpp

@@ -137,7 +137,7 @@ class TimeStretch : public SpinBoxSetting, public PlayGroupDBStorage
         PlayGroupDBStorage::Save();
     }
 
-    virtual void Save(QString /*destination*/) { Save(); }
+    virtual void Save(QString destination) { PlayGroupDBStorage::Save(destination); }
 };
 
 PlayGroupConfig::PlayGroupConfig(QString _name) : name(_name)