Fix memory leak

Reviewed-by: NMatt Caswell <matt@openssl.org>

crypto/dh/dh_ameth.c

@@ -248,6 +248,7 @@ static int dh_priv_decode(EVP_PKEY *pkey, PKCS8_PRIV_KEY_INFO *p8)
     DHerr(DH_F_DH_PRIV_DECODE, EVP_R_DECODE_ERROR);
  dherr:
     DH_free(dh);
+    ASN1_INTEGER_free(privkey);
     return 0;
 }