Avoid returning many "inv" orphans

Rebased-From: 540ac45
Rebased-By: Wladimir J. van der Laan <laanwj@gmail.com>

src/main.cpp

@@ -3606,6 +3606,11 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
 
             // Track requests for our stuff
             g_signals.Inventory(inv.hash);
+
+            if (pfrom->nSendSize > (SendBufferSize() * 2)) {
+                Misbehaving(pfrom->GetId(), 50);
+                return error("send buffer size() = %u", pfrom->nSendSize);
+            }
         }
     }