Explicitly set tx.nVersion for the genesis block and mining tests

If/when CTransaction::CURRENT_VERSION is incremented, this will break CChainParams and the miner tests. This fix sets the transaction version explicitly where we depend on the hash value (genesis block, proof of work checks).

src/chainparams.cpp

@@ -75,6 +75,7 @@ public:
          */
         const char* pszTimestamp = "Zcash0b9c4eef8b7cc417ee5001e3500984b6fea35683a7cac141a043c42064835d34";
         CMutableTransaction txNew;
+        txNew.nVersion = 1;
         txNew.vin.resize(1);
         txNew.vout.resize(1);
         txNew.vin[0].scriptSig = CScript() << 520617983 << CScriptNum(4) << vector<unsigned char>((const unsigned char*)pszTimestamp, (const unsigned char*)pszTimestamp + strlen(pszTimestamp));