add __dummy field to HDNode where fingerprint used to be (in order not to binary compatibility)

bip32.h

@@ -36,6 +36,7 @@ typedef struct {
 
 typedef struct {
 	uint32_t depth;
+	uint32_t __dummy;
 	uint32_t child_num;
 	uint8_t chain_code[32];
 	uint8_t private_key[32];