[build] Add several util units

Adds the following util units and adds them to libbitcoin_util:

- `util/url.cpp` takes `urlDecode` from `httpserver.cpp`
- `util/error.cpp` takes `TransactionErrorString` from
  `node/transaction.cpp` and `AmountHighWarn` and `AmountErrMsg` from
  `ui_interface.cpp`
- `util/fees.cpp` takes `StringForFeeReason` and `FeeModeFromString` from `policy/fees.cpp`
- `util/rbf.cpp` takes `SignalsOptInRBF` from `policy/rbf.cpp`
- 'util/validation.cpp` takes `FormatStateMessage` and `strMessageMagic` from 'validation.cpp`

1 files changed, 0 insertions, 6 deletions

diff --git a/src/policy/rbf.h b/src/policy/rbf.h
index a4f8777310..0707b0044f 100644
--- a/src/policy/rbf.h
+++ b/src/policy/rbf.h
@@ -7,18 +7,12 @@
 
 #include <txmempool.h>
 
-static const uint32_t MAX_BIP125_RBF_SEQUENCE = 0xfffffffd;
-
 enum class RBFTransactionState {
     UNKNOWN,
     REPLACEABLE_BIP125,
     FINAL
 };
 
-// Check whether the sequence numbers on this transaction are signaling
-// opt-in to replace-by-fee, according to BIP 125
-bool SignalsOptInRBF(const CTransaction &tx);
-
 // Determine whether an in-mempool transaction is signaling opt-in to RBF
 // according to BIP 125
 // This involves checking sequence numbers of the transaction, as well