Show "end" instead of many zeros when getheaders request received with a hashStop of Null.

src/main.cpp

@@ -5387,7 +5387,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         // we must use CBlocks, as CBlockHeaders won't include the 0x00 nTx count at the end
         vector<CBlock> vHeaders;
         int nLimit = MAX_HEADERS_RESULTS;
-        LogPrint("net", "getheaders %d to %s from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.ToString(), pfrom->id);
+        LogPrint("net", "getheaders %d to %s from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), pfrom->id);
         for (; pindex; pindex = chainActive.Next(pindex))
         {
             vHeaders.push_back(pindex->GetBlockHeader());