consensus: use <cstdint> over <stdint.h> in amount.h

Author: fanquake

src/consensus/amount.h

@@ -6,7 +6,7 @@
 #ifndef BITCOIN_CONSENSUS_AMOUNT_H
 #define BITCOIN_CONSENSUS_AMOUNT_H
 
-#include <stdint.h>
+#include <cstdint>
 
 /** Amount in satoshis (Can be negative) */
 typedef int64_t CAmount;