Move CBlockFileInfo::ToString method where class is declared

CBlockFileInfo class is declared in src/chain.h, so move ToString
definition to src/chain.cpp instead of src/node/blockstorage.cpp

src/chain.cpp

@@ -4,6 +4,12 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chain.h>
+#include <util/time.h>
+
+std::string CBlockFileInfo::ToString() const
+{
+    return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));
+}
 
 void CChain::SetTip(CBlockIndex *pindex) {
     if (pindex == nullptr) {

src/node/blockstorage.cpp

@@ -473,14 +473,7 @@ void CleanupBlockRevFiles()
         remove(item.second);
     }
 }
-} // namespace node
 
-std::string CBlockFileInfo::ToString() const
-{
-    return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));
-}
-
-namespace node {
 CBlockFileInfo* BlockManager::GetBlockFileInfo(size_t n)
 {
     LOCK(cs_LastBlockFile);