Merge bitcoin-core/secp256k1#1236: Update comment for secp256k1_modinv32_inv256

647f0a5 Update comment for secp256k1_modinv32_inv256 (roconnor-blockstream)

Pull request description:

ACKs for top commit:
  sipa:
    ACK 647f0a5
  real-or-random:
    utACK bitcoin-core/secp256k1@647f0a5

Tree-SHA512: 7c2ec02acf985bb6edfc619ce31bd63511ff634d847a25888927b48b5164353a912d470421b0b969a868fbc5b865cbea188e14357557f44be42d5702af7c5a6b

Author: sipa

src/modinv32_impl.h

@@ -232,7 +232,7 @@ static int32_t secp256k1_modinv32_divsteps_30(int32_t zeta, uint32_t f0, uint32_
     return zeta;
 }
 
-/* inv256[i] = -(2*i+1)^-1 (mod 256) */
+/* secp256k1_modinv32_inv256[i] = -(2*i+1)^-1 (mod 256) */
 static const uint8_t secp256k1_modinv32_inv256[128] = {
     0xFF, 0x55, 0x33, 0x49, 0xC7, 0x5D, 0x3B, 0x11, 0x0F, 0xE5, 0xC3, 0x59,
     0xD7, 0xED, 0xCB, 0x21, 0x1F, 0x75, 0x53, 0x69, 0xE7, 0x7D, 0x5B, 0x31,