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>

include/crypto/hmac.h

@@ -18,6 +18,7 @@ typedef struct QCryptoHmac QCryptoHmac;
 struct QCryptoHmac {
     QCryptoHashAlgorithm alg;
     void *opaque;
+    void *driver;
 };
 
 /**