message: txdb: Remove unused boost/thread
diff: #include <stdint.h>
  -#include <boost/thread.hpp>
  -
  static const char DB_COIN = 'C';
  static const char DB_COINS = 'c';
  static const char DB_BLOCK_FILES = 'f';
  @@ -242,7 +240,6 @@ bool CBlockTreeDB::LoadBlockIndexGuts(const Consensus::Params& consensusParams,
  // Load m_block_index
  while (pcursor->Valid()) {
  - boost::this_thread::interruption_point();
  if (ShutdownRequested()) return false;
  std::pair<char, uint256> key;
  if (pcursor->GetKey(key) && key.first == DB_BLOCK_INDEX) {
  @@ -369,7 +366,6 @@ bool CCoinsViewDB::Upgrade() {
  std::pair<unsigned char, uint256> key;
  std::pair<unsigned char, uint256> prev_key = {DB_COINS, uint256()};
  while (pcursor->Valid()) {
  - boost::this_thread::interruption_point();
  if (ShutdownRequested()) {
  break;
  }
  