[various] remove dead code.

Squashes warnings from clang++

caching/cache_writeback.cc

@@ -103,7 +103,6 @@ namespace {
 			: copier_(c),
 			  block_size_(c.get_block_size()),
 			  only_dirty_(only_dirty),
-			  list_failed_blocks_(list_failed_blocks),
 			  batch_(sort_buffer),
 			  monitor_(monitor),
 			  cache_blocks_(cache_blocks) {
@@ -228,7 +227,6 @@ namespace {
 		copier &copier_;
 		unsigned block_size_;
 		bool only_dirty_;
-		bool list_failed_blocks_;
 
 		copy_stats stats_;
 		copy_batch batch_;

caching/metadata.cc

@@ -8,8 +8,6 @@ namespace pd = persistent_data;
 //----------------------------------------------------------------
 
 namespace {
-	unsigned const METADATA_CACHE_SIZE = 1024;
-
 	// FIXME: duplication
 	transaction_manager::ptr
 	open_tm(block_manager<>::ptr bm) {

caching/restore_emitter.cc

@@ -12,8 +12,7 @@ namespace {
 	class restorer : public emitter {
 	public:
 		restorer(metadata::ptr md, bool clean_shutdown, unsigned metadata_version)
-			: in_superblock_(false),
-			  md_(md),
+			: md_(md),
 			  clean_shutdown_(clean_shutdown),
 			  metadata_version_(metadata_version) {
 		}
@@ -104,7 +103,6 @@ namespace {
 		}
 
 	private:
-		bool in_superblock_;
 		metadata::ptr md_;
 		bool clean_shutdown_;
 		unsigned metadata_version_;

caching/superblock.cc

@@ -289,8 +289,6 @@ superblock_invalid::visit(damage_visitor &v) const
 namespace validator {
 	using namespace persistent_data;
 
-        uint32_t const VERSION = 1;
-        unsigned const SECTOR_TO_BLOCK_SHIFT = 3;
 	uint32_t const SUPERBLOCK_CSUM_SEED = 9031977;
 
 	struct sb_validator : public bcache::validator {