Added Thread::CurrentThreadId() method to wrap up thread id functionality in a more platform appropriate way.

include/OpenThreads/Thread

@@ -113,6 +113,11 @@ public:
      */
     static Thread *CurrentThread();
 
+    /**
+     *  Return the id of the current thread
+     */
+    static size_t CurrentThreadId();
+
 
     /**
      *  Initialize Threading in a program.  This method must be called before
@@ -147,7 +152,7 @@ public:
      *
      *  @return a unique thread identifier
      */
-    int getThreadId();
+    size_t getThreadId();
 
     /**
      *  Get the thread's process id.  This is the pthread_t or pid_t value

include/osg/GraphicsContext

@@ -390,7 +390,7 @@ class OSG_EXPORT GraphicsContext : public Object
         bool releaseContext();
 
         /** Return true if the current thread has this OpenGL graphics context.*/
-        inline bool isCurrent() const { return _threadOfLastMakeCurrent == OpenThreads::Thread::CurrentThread(); }
+        inline bool isCurrent() const { return _threadOfLastMakeCurrent == OpenThreads::Thread::CurrentThreadId(); }
 
         /** Bind the graphics context to associated texture.*/
         inline void bindPBufferToTexture(GLenum buffer) { bindPBufferToTextureImplementation(buffer); }
@@ -547,7 +547,7 @@ class OSG_EXPORT GraphicsContext : public Object
         Vec4                    _clearColor;
         GLbitfield              _clearMask;
 
-        OpenThreads::Thread*    _threadOfLastMakeCurrent;
+        size_t                              _threadOfLastMakeCurrent;
 
         OpenThreads::Mutex                  _operationsMutex;
         osg::ref_ptr<osg::RefBlock>         _operationsBlock;