MDEV-21351 Replace recv_sys.heap with list of buf_block_t

- Fixing the windows compilation failure

storage/innobase/include/log0recv.h

@@ -378,7 +378,7 @@ struct recv_sys_t{
 #endif
 
   /** @return the free length of the latest alloc() block, in bytes */
-  inline ulint get_free_len() const;
+  inline uint32_t get_free_len() const;
 };
 
 /** The recovery system */

storage/innobase/log/log0recv.cc

@@ -870,13 +870,13 @@ void recv_sys_t::debug_free()
 	mutex_exit(&mutex);
 }
 
-inline ulint recv_sys_t::get_free_len() const
+inline uint32_t recv_sys_t::get_free_len() const
 {
   if (UT_LIST_GET_LEN(redo_list) == 0)
     return 0;
 
   return srv_page_size -
-	 static_cast<ulint>(UT_LIST_GET_FIRST(redo_list)->modify_clock);
+	 static_cast<uint32_t>(UT_LIST_GET_FIRST(redo_list)->modify_clock);
 }
 
 inline byte* recv_sys_t::alloc(uint32_t len,bool store_recv)