Merge #15615: Add log output during initial header sync

d75e704 Add log output during initial header sync (Jonas Schnelli)

Pull request description:

  The non debug log output is completely quiet during the header sync. I see two main reasons to add infos about the state of the initial header sync...
  * users may think the node did fail to start sync
  * it's a little complicate to check if your getting throttled during header sync (repeatedly calling `getchaintips` or similar)

ACKs for top commit:
  fanquake:
    Concept ACK bitcoin/bitcoin@d75e704
  practicalswift:
    utACK d75e704
  laanwj:
    Tested ACK d75e704

Tree-SHA512: 2e738571b703d7251290864603c3a829729645962c2fa3187250bab0585e66a5f01fce892e9b5b98da451fab2b40a2e4784f9b2e5a9cad75ff62c535affe7430

Author: laanwj

src/validation.cpp

@@ -3401,6 +3401,12 @@ bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidatio
         }
     }
     NotifyHeaderTip();
+    {
+        LOCK(cs_main);
+        if (::ChainstateActive().IsInitialBlockDownload() && ppindex && *ppindex) {
+            LogPrintf("Synchronizing blockheaders, height: %d (~%.2f%%)\n", (*ppindex)->nHeight, 100.0/((*ppindex)->nHeight+(GetAdjustedTime() - (*ppindex)->GetBlockTime()) / Params().GetConsensus().nPowTargetSpacing) * (*ppindex)->nHeight);
+        }
+    }
     return true;
 }