Expose state-db memory info (#5110)

This exposes memory statistics from the state-db.

substrate/client/state-db/src/pruning.rs

@@ -31,6 +31,7 @@ const LAST_PRUNED: &[u8] = b"last_pruned";
 const PRUNING_JOURNAL: &[u8] = b"pruning_journal";
 
 /// See module documentation.
+#[derive(parity_util_mem_derive::MallocSizeOf)]
 pub struct RefWindow<BlockHash: Hash, Key: Hash> {
 	/// A queue of keys that should be deleted for each block in the pruning window.
 	death_rows: VecDeque<DeathRow<BlockHash, Key>>,
@@ -46,7 +47,7 @@ pub struct RefWindow<BlockHash: Hash, Key: Hash> {
 	pending_prunings: usize,
 }
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, parity_util_mem_derive::MallocSizeOf)]
 struct DeathRow<BlockHash: Hash, Key: Hash> {
 	hash: BlockHash,
 	journal_key: Vec<u8>,