Fix leak of FGTerrain on shutdown

This fixes us leaking all STG objects on shutdown, due to an errant
raw pointer in the scenery layer.

src/Scenery/SceneryPager.cxx

@@ -16,13 +16,12 @@
 // along with this program; if not, write to the Free Software
 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
-#ifdef HAVE_CONFIG_H
-#  include <config.h>
-#endif
+#include <config.h>
 
 #include "SceneryPager.hxx"
 #include <algorithm>
 #include <functional>
+#include <simgear/debug/logstream.hxx>
 
 using namespace osg;
 using namespace flightgear;
@@ -40,6 +39,7 @@ SceneryPager::SceneryPager(const SceneryPager& rhs) :
 
 SceneryPager::~SceneryPager()
 {
+    SG_LOG(SG_TERRAIN, SG_INFO, "Destroying scenery pager");
 }
 
 void SceneryPager::clearRequests()

src/Scenery/scenery.cxx

@@ -407,12 +407,12 @@ void FGScenery::init() {
 
     if ( engine == "pagedLOD" ) {
 #ifdef ENABLE_GDAL
-        _terrain = new FGPgtTerrain();
+        _terrain.reset(new FGPgtTerrain);
 #else
-        _terrain = new FGStgTerrain();
+        _terrain.reset(new FGStgTerrain);
 #endif
     } else {
-        _terrain = new FGStgTerrain();
+        _terrain.reset(new FGStgTerrain);
     }
     _terrain->init( terrain_branch.get() );
 
@@ -438,6 +438,8 @@ void FGScenery::shutdown()
     particles_branch = NULL;
     precipitation_branch = NULL;
 
+    _terrain.reset();
+
     // Toggle the setup flag.
     _inited = false;
 }

src/Scenery/scenery.hxx

@@ -146,7 +146,7 @@ public:
     void materialLibChanged();
 private:
     // the terrain engine
-    FGTerrain* _terrain;
+    std::unique_ptr<FGTerrain> _terrain;
 
     // The state of the scene graph.
     bool _inited;

src/Scenery/terrain.hxx

@@ -49,8 +49,8 @@ class BVHMaterial;
 class FGTerrain
 {
 public:
-    FGTerrain() {};
-    ~FGTerrain() {};
+    FGTerrain() = default;
+    virtual ~FGTerrain() = default;
 
     // Implementation of SGSubsystem. - called from Scenery
     virtual void init ( osg::Group* terrain ) = 0;

src/Scenery/terrain_stg.cxx

@@ -21,9 +21,7 @@
 // $Id$
 
 
-#ifdef HAVE_CONFIG_H
-#  include <config.h>
-#endif
+#include <config.h>
 
 #include <stdio.h>
 #include <string.h>
@@ -232,6 +230,7 @@ FGStgTerrain::FGStgTerrain() :
 
 FGStgTerrain::~FGStgTerrain()
 {
+    SG_LOG(SG_TERRAIN, SG_INFO, "FGStgTerrain::dtor");
 }
 
 

src/Scenery/terrain_stg.hxx

@@ -51,7 +51,7 @@ class FGStgTerrain : public FGTerrain
 public:
 
     FGStgTerrain();
-    ~FGStgTerrain();
+    virtual ~FGStgTerrain();
 
     // Implementation of SGSubsystem.
     void init ( osg::Group* terrain );