build() always trigger the reconstruction of the tree

It can be useful for a mesh with update vertex coordinates

AABB_tree/include/CGAL/AABB_tree.h

@@ -703,12 +703,6 @@ public:
   // Build the data structure, after calls to insert(..)
   template<typename Tr>
   void AABB_tree<Tr>::build()
-  {
-#ifdef CGAL_HAS_THREADS
-    if (m_atomic_need_build.load())
-#else
-    if (m_need_build)
-#endif
   {
     clear_nodes();
     if(m_primitives.size() > 1) {
@@ -733,7 +727,6 @@ public:
     m_need_build = false;
 #endif
   }
-  }
   // constructs the search KD tree from given points
   // to accelerate the distance queries
   template<typename Tr>