replicated get_lock() properly

sql/item_func.cc:
  log all lock releases to binary log for safe handling of get_lock()
  in updates

mysql-test/r/rpl_get_lock.result

+get_lock("lock",3)
+1
+n
+1

mysql-test/t/rpl_get_lock.test

+source include/master-slave.inc;
+connection master;
+create table t1(n int);
+insert into t1 values(get_lock("lock",2));
+dirty_close master;
+connection master1;
+save_master_pos;
+connection slave;
+sync_with_master;
+select get_lock("lock",3);
+select * from t1;
+connection master1;
+drop table t1;
+save_master_pos;
+connection slave;
+sync_with_master;

sql/item_func.cc

@@ -1399,6 +1399,23 @@ void item_user_lock_free(void)
 void item_user_lock_release(ULL *ull)
 {
   ull->locked=0;
+  if (mysql_bin_log.is_open())
+  {
+    THD *thd = current_thd;
+    int save_errno;
+    char buf[256];
+    String tmp(buf,sizeof(buf));
+    tmp.length(0);
+    tmp.append("SELECT release_lock(\"");
+    tmp.append(ull->key,ull->key_length);
+    tmp.append("\")");
+    save_errno=thd->net.last_errno;
+    thd->net.last_errno=0;
+    thd->query_length=tmp.length();
+    Query_log_event qev(thd,tmp.ptr());
+    mysql_bin_log.write(&qev);
+    thd->net.last_errno=save_errno;
+  }
   if (--ull->count)
     pthread_cond_signal(&ull->cond);
   else