crypto/secp256k1: update to github.com/bitcoin-core/secp256k1 @ 9d560f9 (#3544)

- Use defined constants instead of hard-coding their integer value.
- Allocate secp256k1 structs on the C stack instead of converting []byte
- Remove dead code

crypto/secp256k1/libsecp256k1/src/num.h

@@ -32,6 +32,9 @@ static void secp256k1_num_set_bin(secp256k1_num *r, const unsigned char *a, unsi
 /** Compute a modular inverse. The input must be less than the modulus. */
 static void secp256k1_num_mod_inverse(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *m);
 
+/** Compute the jacobi symbol (a|b). b must be positive and odd. */
+static int secp256k1_num_jacobi(const secp256k1_num *a, const secp256k1_num *b);
+
 /** Compare the absolute value of two numbers. */
 static int secp256k1_num_cmp(const secp256k1_num *a, const secp256k1_num *b);
 
@@ -57,6 +60,9 @@ static void secp256k1_num_shift(secp256k1_num *r, int bits);
 /** Check whether a number is zero. */
 static int secp256k1_num_is_zero(const secp256k1_num *a);
 
+/** Check whether a number is one. */
+static int secp256k1_num_is_one(const secp256k1_num *a);
+
 /** Check whether a number is strictly negative. */
 static int secp256k1_num_is_neg(const secp256k1_num *a);