message: Fix compiler warning by removing unused variable.
diff: @@ -419,7 +419,6 @@ bool CTxMemPool::addUnchecked(const uint256& hash, const CTxMemPoolEntry &entry,
  void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason)
  {
  NotifyEntryRemoved(it->GetSharedTx(), reason);
  - const uint256 hash = it->GetTx().GetHash();
  for (const CTxIn& txin : it->GetTx().vin)
  mapNextTx.erase(txin.prevout);
  