Fix compilation under windows clang-19 aarch64 (#235)

Author: andrjohns

src/tbb-compat/tbb-compat.cpp

@@ -40,7 +40,7 @@ class task_scheduler_observer_v3 {
 /** For local observers the method can be used only when the current thread
  has the task scheduler initialized or is attached to an arena.
  Repeated calls with the same state are no-ops. **/
-void __TBB_EXPORTED_METHOD observe( bool state=true );
+voidDLL_EXPORT __TBB_EXPORTED_METHOD observe( bool state=true );
 
 //! Returns true if observation is enabled, false otherwise.
 boolis_observing() const {return my_proxy!=NULL;}