crypto: hmac: add hmac driver framework

1) makes the public APIs in hmac-nettle/gcrypt/glib static,
   and rename them with "nettle/gcrypt/glib" prefix.

2) introduces hmac framework, including QCryptoHmacDriver
   and new public APIs.

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

crypto/hmacpriv.h

@@ -0,0 +1,36 @@
+/*
+ * QEMU Crypto hmac driver supports
+ *
+ * Copyright (c) 2017 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ * Authors:
+ *    Longpeng(Mike) <longpeng2@huawei.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ *
+ */
+
+#ifndef QCRYPTO_HMACPRIV_H
+#define QCRYPTO_HMACPRIV_H
+
+typedef struct QCryptoHmacDriver QCryptoHmacDriver;
+
+struct QCryptoHmacDriver {
+    int (*hmac_bytesv)(QCryptoHmac *hmac,
+                       const struct iovec *iov,
+                       size_t niov,
+                       uint8_t **result,
+                       size_t *resultlen,
+                       Error **errp);
+
+    void (*hmac_free)(QCryptoHmac *hmac);
+};
+
+extern void *qcrypto_hmac_ctx_new(QCryptoHashAlgorithm alg,
+                                  const uint8_t *key, size_t nkey,
+                                  Error **errp);
+extern QCryptoHmacDriver qcrypto_hmac_lib_driver;
+
+#endif