vtkThreadedCallbackQueue: inlining few implementations

2 implementations were in the .txx file and cause linking errors in
  ParaView

Parallel/Core/vtkThreadedCallbackQueue.h

@@ -113,12 +113,27 @@ public:
   public:
     vtkBaseTypeMacro(vtkSharedFutureBase, vtkObjectBase);
 
-    vtkSharedFutureBase();
+    vtkSharedFutureBase()
+      : NumberOfPriorSharedFuturesRemaining(0)
+      , Status(CONSTRUCTING)
+    {
+    }
 
     /**
      * Blocks current thread until the task associated with this future has terminated.
      */
-    virtual void Wait() const;
+    virtual void Wait() const
+    {
+      if (this->Status == READY)
+      {
+        return;
+      }
+      std::unique_lock<std::mutex> lock(this->Mutex);
+      if (this->Status != READY)
+      {
+        this->ConditionVariable.wait(lock, [this] { return this->Status == READY; });
+      }
+    }
 
     friend class vtkThreadedCallbackQueue;
 

Parallel/Core/vtkThreadedCallbackQueue.txx

@@ -24,27 +24,6 @@
 
 VTK_ABI_NAMESPACE_BEGIN
 
-//-----------------------------------------------------------------------------
-vtkThreadedCallbackQueue::vtkSharedFutureBase::vtkSharedFutureBase()
-  : NumberOfPriorSharedFuturesRemaining(0)
-  , Status(CONSTRUCTING)
-{
-}
-
-//-----------------------------------------------------------------------------
-void vtkThreadedCallbackQueue::vtkSharedFutureBase::Wait() const
-{
-  if (this->Status == READY)
-  {
-    return;
-  }
-  std::unique_lock<std::mutex> lock(this->Mutex);
-  if (this->Status != READY)
-  {
-    this->ConditionVariable.wait(lock, [this] { return this->Status == READY; });
-  }
-}
-
 //-----------------------------------------------------------------------------
 template <>
 struct vtkThreadedCallbackQueue::ReturnValueWrapper<void, false>