Depsgraph: Clear operation evaluation flags early on

The goal is to make it possible to evaluate the graph in multiple
passes without evaluating the same node multiple times.

Currently should not be any functional changes.

source/blender/depsgraph/intern/eval/deg_eval.cc

@@ -101,6 +101,12 @@ void evaluate_node(const DepsgraphEvalState *state, OperationNode *operation_nod
   else {
     operation_node->evaluate(depsgraph);
   }
+
+  /* Clear the flag early on, allowing partial updates without re-evaluating the same node multiple
+   * times.
+   * This is a thread-safe modification as the node's flags are only read for a non-scheduled nodes
+   * and this node has been scheduled. */
+  operation_node->flag &= ~DEPSOP_FLAG_NEEDS_UPDATE;
 }
 
 void deg_task_run_func(TaskPool *pool, void *taskdata)