Add UpdatedBlockTip signal to CMainSignals and CValidationInterface

src/main.cpp

@@ -2303,6 +2303,7 @@ bool ActivateBestChain(CValidationState &state, const CBlock *pblock) {
                         pnode->PushInventory(CInv(MSG_BLOCK, hashNewTip));
             }
             // Notify external listeners about the new tip.
+            GetMainSignals().UpdatedBlockTip(hashNewTip);
             uiInterface.NotifyBlockTip(hashNewTip);
         }
     } while(pindexMostWork != chainActive.Tip());