Avoid returning many "inv" orphans

Rebased-from: 540ac4514d

src/main.cpp

@@ -3464,6 +3464,11 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
 
             // Track requests for our stuff
             Inventory(inv.hash);
+
+            if (pfrom->nSendSize > (SendBufferSize() * 2)) {
+                pfrom->Misbehaving(50);
+                return error("send buffer size() = %"PRIszu"", pfrom->nSendSize);
+            }
         }
     }