musig: ensure point_load output is normalized

This is similar to the upstream commit "Normalize ge produced from
secp256k1_pubkey_load".

Author: jonasnick

src/modules/musig/keyagg_impl.h

@@ -41,8 +41,10 @@ static void secp256k1_point_load(secp256k1_ge *ge, const unsigned char *data) {
     } else {
         /* Otherwise, fall back to 32-byte big endian for X and Y. */
         secp256k1_fe x, y;
-        secp256k1_fe_set_b32_mod(&x, data);
-        secp256k1_fe_set_b32_mod(&y, data + 32);
+        int ret = 1;
+        ret &= secp256k1_fe_set_b32_limit(&x, data);
+        ret &= secp256k1_fe_set_b32_limit(&y, data + 32);
+        VERIFY_CHECK(ret);
         secp256k1_ge_set_xy(ge, &x, &y);
     }
 }