Add missing LOCK(cs_main)

src/main.cpp

@@ -3488,7 +3488,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         return true;
     }
 
+    {
+        LOCK(cs_main);
         State(pfrom->GetId())->nLastBlockProcess = GetTimeMicros();
+    }