Update to new API

test/cpp/microbenchmarks/bm_cq_multiple_threads.cc

@@ -67,7 +67,9 @@ static void pollset_init(grpc_pollset* ps, gpr_mu** mu) {
   *mu = &ps->mu;
 }
 
-static void pollset_destroy(grpc_pollset* ps) { gpr_mu_destroy(&ps->mu); }
+static void pollset_destroy(grpc_exec_ctx* exec_ctx, grpc_pollset* ps) {
+  gpr_mu_destroy(&ps->mu);
+}
 
 static grpc_error* pollset_kick(grpc_pollset* p, grpc_pollset_worker* worker) {
   return GRPC_ERROR_NONE;