GCC: fix some unused warnings

hash_extra: don't test for success in `jh_hash` and `skein_hash` since its guaranteed
device_ledger: move anonymous global variable apdu_verbose into .cpp file
Add comments to `refreshed` method variable in wallet2

src/crypto/hash-extra-jh.c

@@ -36,7 +36,9 @@
 #include "jh.h"
 #include "hash-ops.h"
 
+#define JH_HASH_BITLEN HASH_SIZE * 8
+
 void hash_extra_jh(const void *data, size_t length, char *hash) {
-  int r = jh_hash(HASH_SIZE * 8, data, 8 * length, (uint8_t*)hash);
-  assert(SUCCESS == r);
+  // No need to check for failure b/c jh_hash only fails for invalid hash size
+  jh_hash(JH_HASH_BITLEN, data, 8 * length, (uint8_t*)hash);
 }

src/crypto/hash-extra-skein.c

@@ -34,7 +34,9 @@
 #include "hash-ops.h"
 #include "skein.h"
 
+#define SKEIN_HASH_BITLEN HASH_SIZE * 8
+
 void hash_extra_skein(const void *data, size_t length, char *hash) {
-  int r = skein_hash(8 * HASH_SIZE, data, 8 * length, (uint8_t*)hash);
-  assert(SKEIN_SUCCESS == r);
+  // No need to check for failure b/c skein_hash only fails for invalid hash size
+  skein_hash(SKEIN_HASH_BITLEN, data, 8 * length, (uint8_t*)hash);
 }

src/device/device_ledger.cpp

@@ -43,6 +43,10 @@ namespace hw {
 
   #ifdef WITH_DEVICE_LEDGER
 
+    namespace {
+        bool apdu_verbose =true;
+    }
+
     #undef MONERO_DEFAULT_LOG_CATEGORY
     #define MONERO_DEFAULT_LOG_CATEGORY "device.ledger"
 

src/device/device_ledger.hpp

@@ -87,10 +87,6 @@ namespace hw {
     #define SW_PROTOCOL_NOT_SUPPORTED               0x6e00
     #define SW_UNKNOWN                              0x6f00
 
-    namespace {
-        bool apdu_verbose =true;
-    }
-
     void set_apdu_verbose(bool verbose);
 
     class ABPkeys {

src/wallet/wallet2.cpp

@@ -3418,6 +3418,10 @@ void wallet2::refresh(bool trusted_daemon, uint64_t start_height, uint64_t & blo
   uint64_t blocks_start_height;
   std::vector<cryptonote::block_complete_entry> blocks;
   std::vector<parsed_block> parsed_blocks;
+  // TODO moneromooo-monero says this about the "refreshed" variable:
+  // "I had to reorder some code to fix... a timing info leak IIRC. In turn, this undid something I had fixed before, ... a subtle race condition with the txpool.
+  // It was pretty subtle IIRC, and so I needed time to think about how to refix it after the move, and I never got to it."
+  // https://github.com/monero-project/monero/pull/6097
   bool refreshed = false;
   std::shared_ptr<std::map<std::pair<uint64_t, uint64_t>, size_t>> output_tracker_cache;
   hw::device &hwdev = m_account.get_device();