message: Only use filterInventoryKnown with MSG_TX inventory messages.
  Previously this logic could erroneously filter a MSG_BLOCK inventory message.
diff: @@ -494,7 +494,8 @@ public:
  {
  {
  LOCK(cs_inventory);
  - if (!filterInventoryKnown.contains(inv.hash))
  + if (inv.type == MSG_TX && filterInventoryKnown.contains(inv.hash))
  + return;
  vInventoryToSend.push_back(inv);
  }
  }
  