[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, 1 insertions, 10 deletions

diff --git a/src/policy/rbf.cpp b/src/policy/rbf.cpp
index c73a97fd7d..b4b8341d77 100644
--- a/src/policy/rbf.cpp
+++ b/src/policy/rbf.cpp
@@ -3,16 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <policy/rbf.h>
-
-bool SignalsOptInRBF(const CTransaction &tx)
-{
-    for (const CTxIn &txin : tx.vin) {
-        if (txin.nSequence <= MAX_BIP125_RBF_SEQUENCE) {
-            return true;
-        }
-    }
-    return false;
-}
+#include <util/rbf.h>
 
 RBFTransactionState IsRBFOptIn(const CTransaction& tx, const CTxMemPool& pool)
 {