Skip UpdateStaticness per-agent work when detect_static_agents is false

UpdateStaticnessOp called Simulation::GetActive()->GetParam() and
wrote two booleans for every agent every step, even when
detect_static_agents was false (the default). Both values are
already initialized to false, so the writes were redundant. Cache
the flag once per step in SetUp and return immediately from the
per-agent call when the feature is disabled.

Author: stanbot8

src/core/operation/default_ops.cc

@@ -48,7 +48,18 @@ BDM_REGISTER_OP(MechanicalForcesOpOpenCL, "mechanical forces", kOpenCl);
 struct UpdateStaticnessOp : public AgentOperationImpl {
   BDM_OP_HEADER(UpdateStaticnessOp);
 
-  void operator()(Agent* agent) override { agent->UpdateStaticness(); }
+  void SetUp() override {
+    detect_static_ = Simulation::GetActive()->GetParam()->detect_static_agents;
+  }
+
+  void operator()(Agent* agent) override {
+    if (!detect_static_) {
+      return;
+    }
+    agent->UpdateStaticness();
+  }
+
+  bool detect_static_ = false;
 };
 
 BDM_REGISTER_OP(UpdateStaticnessOp, "update staticness", kCpu);