Fix mempool.cs vs cs_inventory potential deadlock

POTENTIAL DEADLOCK DETECTED
Previous lock order was:
 pnode->cs_sendProcessing  net.cpp:2724
 cs_main  net_processing.cpp:3867 (TRY)
 (1) pto->cs_inventory  net_processing.cpp:4106
 (2) cs  txmempool.cpp:1137
Current lock order is:
 cs_main  wallet/rpcwallet.cpp:468
 (2) mempool.cs  wallet/rpcwallet.cpp:468
 pwallet->cs_wallet  wallet/rpcwallet.cpp:469
 cs_main  wallet/wallet.cpp:4045
 (2) mempool.cs  wallet/wallet.cpp:4045
 cs_wallet  wallet/wallet.cpp:4046
 cs_vNodes  net.cpp:3464
 (1) cs_inventory  ./net.h:1056

Author: UdjinM6

src/net_processing.cpp

@@ -4103,7 +4103,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto, std::atomic<bool>& interruptM
             reserve = std::min<size_t>(reserve, MAX_INV_SZ);
             vInv.reserve(reserve);
 
-            LOCK(pto->cs_inventory);
+            LOCK2(mempool.cs, pto->cs_inventory);
 
             // Add blocks
             for (const uint256& hash : pto->vInventoryBlockToSend) {