Don't call _ma_decrement_open_count() for ma_extra(HA_EXTRA_PREPARE_FOR_DROP).

Don't call _mi_decrement_open_count() for mi_extra(HA_EXTRA_PREPARE_FOR_DROP).
This ensures that if we empty the key cache and a drop table fails later, the index will be automaticly rebuilt

storage/maria/ma_extra.c:
  Don't call _ma_decrement_open_count() for ma_extra(HA_EXTRA_PREPARE_FOR_DROP).
  This ensures that if we empty the key cache and a drop table fails later, the index will be automaticly rebuilt
storage/maria/ma_locking.c:
  Simple optimization: Don't call maria_lock_database() if locking is disabled
storage/myisam/mi_extra.c:
  Don't call _mi_decrement_open_count() for mi_extra(HA_EXTRA_PREPARE_FOR_DROP).
  Simplify code to remove if

storage/maria/ma_extra.c

@@ -323,9 +323,16 @@ int maria_extra(MARIA_HA *info, enum ha_extra_function function,
         error= my_errno;
       info->lock_type= F_UNLCK;
     }
-    if (share->kfile.file >= 0)
-      _ma_decrement_open_count(info);
+    /*
+      We don't need to call _mi_decrement_open_count() if we are
+      dropping the table, as the files will be removed anyway. If we
+      are aborted before the files is removed, it's better to not
+      call it as in that case the automatic repair on open will add
+      the missing index entries
+    */
     pthread_mutex_lock(&share->intern_lock);
+    if (share->kfile.file >= 0 && function != HA_EXTRA_PREPARE_FOR_DROP)
+      _ma_decrement_open_count(info);
     if (info->trn)
     {
       _ma_remove_table_from_trnman(share, info->trn);

storage/maria/ma_locking.c

@@ -484,7 +484,7 @@ int _ma_decrement_open_count(MARIA_HA *info)
   {
     uint old_lock=info->lock_type;
     share->global_changed=0;
-    lock_error=maria_lock_database(info,F_WRLCK);
+    lock_error= my_disable_locking ? 0 : maria_lock_database(info, F_WRLCK);
     /* Its not fatal even if we couldn't get the lock ! */
     if (share->state.open_count > 0)
     {
@@ -499,7 +499,7 @@ int _ma_decrement_open_count(MARIA_HA *info)
                                      MYF(MY_NABP));
       }
     }
-    if (!lock_error)
+    if (!lock_error && !my_disable_locking)
       lock_error=maria_lock_database(info,old_lock);
   }
   return test(lock_error || write_error);

storage/myisam/mi_extra.c

@@ -286,9 +286,19 @@ int mi_extra(MI_INFO *info, enum ha_extra_function function, void *extra_arg)
       info->lock_type = F_UNLCK;
     }
     if (share->kfile >= 0)
+    {
+      /*
+        We don't need to call _mi_decrement_open_count() if we are
+        dropping the table, as the files will be removed anyway. If we
+        are aborted before the files is removed, it's better to not
+        call it as in that case the automatic repair on open will add
+        the missing index entries
+      */
+      if (function != HA_EXTRA_PREPARE_FOR_DROP)
       _mi_decrement_open_count(info);
-    if (share->kfile >= 0 && my_close(share->kfile,MYF(0)))
+      if (my_close(share->kfile,MYF(0)))
         error=my_errno;
+    }
     {
       LIST *list_element ;
       for (list_element=myisam_open_list ;