Add src/node/* code to node:: namespace

src/node/miner.cpp

@@ -26,6 +26,7 @@
 #include <algorithm>
 #include <utility>
 
+namespace node {
 int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
 {
     int64_t nOldTime = pblock->nTime;
@@ -464,3 +465,4 @@ void IncrementExtraNonce(CBlock* pblock, const CBlockIndex* pindexPrev, unsigned
     pblock->vtx[0] = MakeTransactionRef(std::move(txCoinbase));
     pblock->hashMerkleRoot = BlockMerkleRoot(*pblock);
 }
+} // namespace node