Fix ECC sign with custom curves so the custom params (dp) are passed to public key used for sign.

wolfcrypt/src/ecc.c

@@ -3538,6 +3538,13 @@ int wc_ecc_sign_hash_ex(const byte* in, word32 inlen, WC_RNG* rng,
 
        /* don't use async for key, since we don't support async return here */
        if (wc_ecc_init_ex(&pubkey, key->heap, INVALID_DEVID) == MP_OKAY) {
+       #ifdef WOLFSSL_CUSTOM_CURVES
+           /* if custom curve, apply params to pubkey */
+           if (key->idx == ECC_CUSTOM_IDX) {
+               wc_ecc_set_custom_curve(&pubkey, key->dp);
+           }
+       #endif
+
            for (;;) {
                if (++loop_check > 64) {
                     err = RNG_FAILURE_E;