Merge #8126: std::shared_ptr based CTransaction storage in mempool
288d85d Get rid of CTxMempool::lookup() entirely (Pieter Wuille)
c2a4724 Optimization: use usec in expiration and reuse nNow (Pieter Wuille)
e9b4780 Optimization: don't check the mempool at all if no mempool req ever (Pieter Wuille)
dbfb426 Optimize the relay map to use shared_ptr's (Pieter Wuille)
8d39d7a Switch CTransaction storage in mempool to std::shared_ptr (Pieter Wuille)
1b9e6d3 Add support for unique_ptr and shared_ptr to memusage (Pieter Wuille)