Track mined blocks to detect and report orphans and mining revenue

Part of #1713
Closes #1716

src/metrics.h

@@ -2,6 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include "uint256.h"
+
 #include <atomic>
 #include <string>
 
@@ -26,7 +28,8 @@ struct AtomicCounter {
 extern AtomicCounter transactionsValidated;
 extern AtomicCounter ehSolverRuns;
 extern AtomicCounter solutionTargetChecks;
-extern AtomicCounter minedBlocks;
+
+void TrackMinedBlock(uint256 hash);
 
 void ConnectMetricsScreen();
 void ThreadShowMetricsScreen();