Fixes for OSX.

src/osgFX/Registry.cpp

@@ -2,8 +2,13 @@
 
 using namespace osgFX;
 
-Registry *Registry::instance_ = 0;
 
+Registry *Registry::instance()
+{
+    static osg::ref_ptr<Registry> s_instance = new Registry;
+    return s_instance.get();
+}
+    
 Registry::Registry()
 {
 }