Ensure that data types are consistent

1. nStatus of CBlockIndex  is consistent with the definition of Enum(BlockStatus)

2. The BlockHeader is consistent with the type of variable defined in CBlockHeader

Author: jjz

src/chain.h

@@ -204,14 +204,14 @@ class CBlockIndex
     unsigned int nChainTx;
 
     //! Verification status of this block. See enum BlockStatus
-    unsigned int nStatus;
+    uint32_t nStatus;
 
     //! block header
-    int nVersion;
+    int32_t nVersion;
     uint256 hashMerkleRoot;
-    unsigned int nTime;
-    unsigned int nBits;
-    unsigned int nNonce;
+    uint32_t nTime;
+    uint32_t nBits;
+    uint32_t nNonce;
 
     //! (memory only) Sequential id assigned to distinguish order in which blocks are received.
     int32_t nSequenceId;