Merge #19317: Add a left-justified width field to log2_work component for a uniform debug.log output

c858302 Change format of log2_work for uniform output (zero-padded) (jmorgan)

Pull request description:

  Motivation:
  It's jarring to watch the output of `tail -f ~/btcdata/debug.log` scroll by and very frequently see columns not lining up correctly because `log2_work` somtimes has less precision than 8 digits.

  Current display:
  ```
  2020-06-18T02:54:42Z UpdateTip: new best=0000000000000000107f877e4920643f9fb06090fa7551cd1cdd83b857f520aa height=382038 version=0x00000003 log2_work=83.558653 tx=90953616 date='2015-11-04T17:11:44Z' progress=0.166675 cache=117.6MiB(966410txo)
  2020-06-18T02:54:51Z UpdateTip: new best=0000000000000000019a4de585d30d1a8cc13c7a1972d11b4945635c9556acb5 height=382039 version=0x00000003 log2_work=83.55868 tx=90955936 date='2015-11-04T17:19:39Z' progress=0.166679 cache=117.9MiB(968799txo)
  ```

  Display with this commit:
  ```
  2020-06-18T02:54:42Z UpdateTip: new best=0000000000000000107f877e4920643f9fb06090fa7551cd1cdd83b857f520aa height=382038 version=0x00000003 log2_work=83.558653 tx=90953616 date='2015-11-04T17:11:44Z' progress=0.166675 cache=117.6MiB(966410txo)
  2020-06-18T02:54:51Z UpdateTip: new best=0000000000000000019a4de585d30d1a8cc13c7a1972d11b4945635c9556acb5 height=382039 version=0x00000003 log2_work=83.55868  tx=90955936 date='2015-11-04T17:19:39Z' progress=0.166679 cache=117.9MiB(968799txo)
  ```

ACKs for top commit:
  practicalswift:
    ACK c858302 -- patch looks great :)
  achow101:
    ACK c858302
  laanwj:
    Tested ACK c858302

Tree-SHA512: 16cbe419c4993ad51019c676e8ca409ef1025b803cc598437c780dd7ca003d7e4ad421f451e9a374e0070ee9b3ee601b7aba849e1f346798f9321d1bce5c4401

Author: laanwj

src/validation.cpp

@@ -1421,12 +1421,12 @@ void static InvalidChainFound(CBlockIndex* pindexNew) EXCLUSIVE_LOCKS_REQUIRED(c
         pindexBestHeader = ::ChainActive().Tip();
     }
 
-    LogPrintf("%s: invalid block=%s  height=%d  log2_work=%.8g  date=%s\n", __func__,
+    LogPrintf("%s: invalid block=%s  height=%d  log2_work=%f  date=%s\n", __func__,
       pindexNew->GetBlockHash().ToString(), pindexNew->nHeight,
       log(pindexNew->nChainWork.getdouble())/log(2.0), FormatISO8601DateTime(pindexNew->GetBlockTime()));
     CBlockIndex *tip = ::ChainActive().Tip();
     assert (tip);
-    LogPrintf("%s:  current best=%s  height=%d  log2_work=%.8g  date=%s\n", __func__,
+    LogPrintf("%s:  current best=%s  height=%d  log2_work=%f  date=%s\n", __func__,
       tip->GetBlockHash().ToString(), ::ChainActive().Height(), log(tip->nChainWork.getdouble())/log(2.0),
       FormatISO8601DateTime(tip->GetBlockTime()));
     CheckForkWarningConditions();
@@ -2476,7 +2476,7 @@ void static UpdateTip(const CBlockIndex* pindexNew, const CChainParams& chainPar
         if (nUpgraded > 0)
             AppendWarning(warning_messages, strprintf(_("%d of last 100 blocks have unexpected version"), nUpgraded));
     }
-    LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%.8g tx=%lu date='%s' progress=%f cache=%.1fMiB(%utxo)%s\n", __func__,
+    LogPrintf("%s: new best=%s height=%d version=0x%08x log2_work=%f tx=%lu date='%s' progress=%f cache=%.1fMiB(%utxo)%s\n", __func__,
       pindexNew->GetBlockHash().ToString(), pindexNew->nHeight, pindexNew->nVersion,
       log(pindexNew->nChainWork.getdouble())/log(2.0), (unsigned long)pindexNew->nChainTx,
       FormatISO8601DateTime(pindexNew->GetBlockTime()),