Testchains: Don't check the genesis block

Rebased by Pieter Wuille.
Cleanup by Matt Corallo.

Author: jtimon

src/pow.cpp

@@ -80,6 +80,9 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits, const Consensus::Params&
     bool fOverflow;
     arith_uint256 bnTarget;
 
+    if (hash == params.hashGenesisBlock)
+        return true;
+
     bnTarget.SetCompact(nBits, &fNegative, &fOverflow);
 
     // Check range

src/txdb.cpp

@@ -199,7 +199,7 @@ bool CBlockTreeDB::LoadBlockIndexGuts(boost::function<CBlockIndex*(const uint256
                 pindexNew->nStatus        = diskindex.nStatus;
                 pindexNew->nTx            = diskindex.nTx;
 
-                if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits, Params().GetConsensus()))
+                if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits, consensusParams))
                     return error("LoadBlockIndex(): CheckProofOfWork failed: %s", pindexNew->ToString());
 
                 pcursor->Next();

src/txdb.h

@@ -20,6 +20,7 @@
 class CBlockIndex;
 class CCoinsViewDBCursor;
 class uint256;
+namespace Consensus { struct Params; }
 
 //! -dbcache default (MiB)
 static const int64_t nDefaultDbCache = 300;