Add founders reward to ChainParams.

Fix bug where subsidy slow shift was ignored.

src/consensus/params.h

@@ -32,6 +32,9 @@ struct Params {
      */
     int SubsidySlowStartShift() const { return nSubsidySlowStartInterval / 2; }
     int nSubsidyHalvingInterval;
+    int GetLastFoundersRewardBlockHeight() const {
+        return nSubsidyHalvingInterval + SubsidySlowStartShift() - 1;
+    }
     /** Used to check majorities for block version upgrade */
     int nMajorityEnforceBlockUpgrade;
     int nMajorityRejectBlockOutdated;