Add activation code for the new DAA.

Summary: This adds the activation of the new DAA in ABC.

Test Plan: Tested activation large scale with bitprim.

Reviewers: freetrader, schancel, #bitcoin_abc

Reviewed By: schancel, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D628

src/pow.cpp

@@ -10,6 +10,7 @@
 #include "chain.h"
 #include "primitives/block.h"
 #include "uint256.h"
+#include "util.h"
 
 /**
  * Compute the next required proof of work using the legacy Bitcoin difficulty
@@ -97,6 +98,11 @@ uint32_t GetNextWorkRequired(const CBlockIndex *pindexPrev,
         return pindexPrev->nBits;
     }
 
+    if (pindexPrev->GetMedianTimePast() >=
+        GetArg("-newdaaactivationtime", params.cashHardForkActivationTime)) {
+        return GetNextCashWorkRequired(pindexPrev, pblock, params);
+    }
+
     return GetNextEDAWorkRequired(pindexPrev, pblock, params);
 }