internal miner: move 2 globals from main to miner

- moves 2 global variables from main.cpp/h to miner.cpp/h
- also removes 2 unneded includes in miner.cpp, that come from miner.h
  already

src/miner.h

@@ -22,4 +22,7 @@ bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey);
 /** Base sha256 mining transform */
 void SHA256Transform(void* pstate, void* pinput, const void* pinit);
 
+extern double dHashesPerSec;
+extern int64 nHPSTimerStart;
+
 #endif // BITCOIN_MINER_H