apply holyfoot's patch for BUG#25895

sql/item_func.cc

@@ -3084,7 +3084,13 @@ class User_level_lock
   int count;
   bool locked;
   pthread_cond_t cond;
+#ifndef EMBEDDED_LIBRARY
   pthread_t thread;
+  void set_thread(THD *thd) { thread= thd->real_id; }
+#else
+  THD       *thread;
+  void set_thread(THD *thd) { thread= thd; }
+#endif /*EMBEDDED_LIBRARY*/
   ulong thread_id;
 
   User_level_lock(const char *key_arg,uint length, ulong id) 
@@ -3238,7 +3244,7 @@ void debug_sync_point(const char* lock_name, uint lock_timeout)
   else
   {
     ull->locked=1;
-    ull->thread=thd->real_id;
+    ull->set_thread(thd);
     thd->ull=ull;
   }
   pthread_mutex_unlock(&LOCK_user_locks);
@@ -3313,7 +3319,7 @@ longlong Item_func_get_lock::val_int()
       null_value=1;				// Probably out of memory
       return 0;
     }
-    ull->thread=thd->real_id;
+    ull->set_thread(thd);
     thd->ull=ull;
     pthread_mutex_unlock(&LOCK_user_locks);
     return 1;					// Got new lock
@@ -3354,7 +3360,7 @@ longlong Item_func_get_lock::val_int()
   else                                          // We got the lock
   {
     ull->locked=1;
-    ull->thread=thd->real_id;
+    ull->set_thread(thd);
     ull->thread_id= thd->thread_id;
     thd->ull=ull;
     error=0;
@@ -3403,7 +3409,7 @@ longlong Item_func_release_lock::val_int()
   else
   {
 #ifdef EMBEDDED_LIBRARY
-    if (ull->locked && pthread_equal(current_thd->real_id,ull->thread))
+    if (ull->locked && (current_thd == ull->thread))
 #else
     if (ull->locked && pthread_equal(pthread_self(),ull->thread))
 #endif