Switch blocks to a constant-space Merkle root/branch algorithm.

This switches the Merkle tree logic for blocks to one that runs in constant (small) space.
The old code is moved to tests, and a new test is added that for various combinations of
block sizes, transaction positions to compute a branch for, and mutations:
 * Verifies that the old code and new code agree for the Merkle root.
 * Verifies that the old code and new code agree for the Merkle branch.
 * Verifies that the computed Merkle branch is valid.
 * Verifies that mutations don't change the Merkle root.
 * Verifies that mutations are correctly detected.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 5d6d1ef9d8..a46866a2be 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -4,6 +4,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "chainparams.h"
+#include "consensus/merkle.h"
 
 #include "tinyformat.h"
 #include "util.h"
@@ -32,7 +33,7 @@ static CBlock CreateGenesisBlock(const char* pszTimestamp, const CScript& genesi
     genesis.nVersion = nVersion;
     genesis.vtx.push_back(txNew);
     genesis.hashPrevBlock.SetNull();
-    genesis.hashMerkleRoot = genesis.ComputeMerkleRoot();
+    genesis.hashMerkleRoot = BlockMerkleRoot(genesis);
     return genesis;
 }