kernel: De-globalize fReindex

fReindex is one of the last remaining globals exposed by the kernel
library, so move it into the blockstorage class to reduce the amount of
global mutable state and make the kernel library a bit less awkward to
use.

src/node/blockstorage.cpp

@@ -150,7 +150,6 @@ bool BlockTreeDB::LoadBlockIndexGuts(const Consensus::Params& consensusParams, s
 } // namespace kernel
 
 namespace node {
-std::atomic_bool fReindex(false);
 
 bool CBlockIndexWorkComparator::operator()(const CBlockIndex* pa, const CBlockIndex* pb) const
 {
@@ -552,7 +551,7 @@ bool BlockManager::LoadBlockIndexDB(const std::optional<uint256>& snapshot_block
     // Check whether we need to continue reindexing
     bool fReindexing = false;
     m_block_tree_db->ReadReindexing(fReindexing);
-    if (fReindexing) fReindex = true;
+    if (fReindexing) m_reindexing = true;
 
     return true;
 }
@@ -1178,7 +1177,7 @@ void ImportBlocks(ChainstateManager& chainman, std::vector<fs::path> vImportFile
     ImportingNow imp{chainman.m_blockman.m_importing};
 
     // -reindex
-    if (fReindex) {
+    if (chainman.m_blockman.m_reindexing) {
         int nFile = 0;
         // Map of disk positions for blocks with unknown parent (only used for reindex);
         // parent hash -> child disk position, multiple children can have the same parent.
@@ -1201,7 +1200,7 @@ void ImportBlocks(ChainstateManager& chainman, std::vector<fs::path> vImportFile
             nFile++;
         }
         WITH_LOCK(::cs_main, chainman.m_blockman.m_block_tree_db->WriteReindexing(false));
-        fReindex = false;
+        chainman.m_blockman.m_reindexing = false;
         LogPrintf("Reindexing finished\n");
         // To avoid ending up in a situation without genesis block, re-try initializing (no-op if reindexing worked):
         chainman.ActiveChainstate().LoadGenesisBlock();