Make *Final work for key wrap again.

Reviewed-by: NTim Hudson <tjh@openssl.org>

crypto/evp/e_aes.c

@@ -2097,6 +2097,8 @@ static int aes_wrap_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
 	{
 	EVP_AES_WRAP_CTX *wctx = ctx->cipher_data;
 	size_t rv;
+	if (!in)
+		return 0;
 	if (inlen % 8)
 		return -1;
 	if (ctx->encrypt && inlen < 8)
@@ -2110,8 +2112,6 @@ static int aes_wrap_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
 		else
 			return inlen - 8;
 		}
-	if (!in)
-		return 0;
 	if (ctx->encrypt)
 		rv = CRYPTO_128_wrap(&wctx->ks.ks, wctx->iv, out, in, inlen,
 						(block128_f)AES_encrypt);