Merge rust-bitcoin#2828: fuzz: add more coverage for deserialize_block

ee30eaa fuzz: add more coverage for `deserialize_block` (Bruno Garcia)

Pull request description:

  This PR adds more coverage for the `deserialize_block` target. First, it serializes the block and compares with the data provided and then call some block functions to ensure they run without any issue.

ACKs for top commit:
  apoelstra:
    ACK ee30eaa Thanks!

Tree-SHA512: db6c7befa7b429267e9b28fb7910d2b9e8d462e22c791b544b1aa528c7ba4f8e1cd32e1276c67d3da1f97ce484e7ed19ec20b10d2030f2977fd8f855cf510ffe

Author: apoelstra

fuzz/fuzz_targets/bitcoin/deserialize_block.rs

@@ -1,8 +1,22 @@
 use honggfuzz::fuzz;
 
 fn do_test(data: &[u8]) {
-    let _: Result<bitcoin::blockdata::block::Block, _> =
+    let block_result: Result<bitcoin::blockdata::block::Block, _> =
         bitcoin::consensus::encode::deserialize(data);
+
+    match block_result {
+        Err(_) => {}
+        Ok(block) => {
+            let ser = bitcoin::consensus::encode::serialize(&block);
+            assert_eq!(&ser[..], data);
+            let _ = block.bip34_block_height();
+            block.block_hash();
+            block.check_merkle_root();
+            block.check_witness_commitment();
+            block.weight();
+            block.witness_root();
+        }
+    }
 }
 
 fn main() {