validation: Pass in chainstate to CTxMemPool::check

This is the only instance where validation reaches for something outside
of it.

src/net_processing.cpp

@@ -2301,7 +2301,7 @@ void PeerManagerImpl::ProcessOrphanTx(std::set<uint256>& orphan_work_set)
             break;
         }
     }
-    m_mempool.check(&::ChainstateActive().CoinsTip());
+    m_mempool.check(m_chainman.ActiveChainstate());
 }
 
 /**
@@ -3262,7 +3262,7 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
         const TxValidationState& state = result.m_state;
 
         if (result.m_result_type == MempoolAcceptResult::ResultType::VALID) {
-            m_mempool.check(&::ChainstateActive().CoinsTip());
+            m_mempool.check(m_chainman.ActiveChainstate());
             // As this version of the transaction was acceptable, we can forget about any
             // requests for it.
             m_txrequest.ForgetTxHash(tx.GetHash());