blockchain: invalidate misc caches when popping blocks

Might be a bit heavy handed, but conservative.

src/cryptonote_core/blockchain.cpp

@@ -584,6 +584,12 @@ block Blockchain::pop_block_from_blockchain()
       }
     }
   }
+
+  m_blocks_longhash_table.clear();
+  m_scan_table.clear();
+  m_blocks_txs_check.clear();
+  m_check_txin_table.clear();
+
   update_next_cumulative_size_limit();
   m_tx_pool.on_blockchain_dec(m_db->height()-1, get_tail_id());