fix crash on exit

panda/src/display/graphicsStateGuardian.cxx

@@ -70,6 +70,15 @@ GraphicsStateGuardian(GraphicsWindow *win) {
   reset();
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: GraphicsStateGuardian::Destructor
+//       Access: Public
+//  Description: 
+////////////////////////////////////////////////////////////////////
+GraphicsStateGuardian::
+~GraphicsStateGuardian() {
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: GraphicsStateGuardian::release_all_textures
 //       Access: Public

panda/src/display/graphicsStateGuardian.h

@@ -41,6 +41,7 @@ class EXPCL_PANDA GraphicsStateGuardian : public GraphicsStateGuardianBase {
   //
 public:
   GraphicsStateGuardian(GraphicsWindow *win);
+  ~GraphicsStateGuardian();
 
 PUBLISHED:
   INLINE void set_render_traverser(RenderTraverser *rt);