Fix timestamp in fee estimate debug message

src/policy/fees.cpp

@@ -944,7 +944,7 @@ void CBlockPolicyEstimator::FlushUnconfirmed(CTxMemPool& pool) {
         removeTx(txid, false);
     }
     int64_t endclear = GetTimeMicros();
-    LogPrint(BCLog::ESTIMATEFEE, "Recorded %u unconfirmed txs from mempool in %ld micros\n",txids.size(), endclear - startclear);
+    LogPrint(BCLog::ESTIMATEFEE, "Recorded %u unconfirmed txs from mempool in %gs\n",txids.size(), (endclear - startclear)*0.000001);
 }
 
 FeeFilterRounder::FeeFilterRounder(const CFeeRate& minIncrementalFee)