fix cut handling with threads

do not compile or.threadengine unless yapor on.

OPTYap/or.cowengine.c

@@ -120,7 +120,7 @@ int p_share_work(void) {
 
 int q_share_work(int worker_p) {
   LOCK_OR_FRAME(LOCAL_top_or_fr);
-  if (REMOTE_prune_request(worker_p)) {
+  if (Get_REMOTE_prune_request(worker_p)) {
     /* worker p with prune request */
     UNLOCK_OR_FRAME(LOCAL_top_or_fr);
     return FALSE;