Generate a single summary audit line for AS/TGS.

We refactor the code a bit to extend kdc_request_t which until now
was only used for the AS.  We make the structure extensible and
start using it for the TGS as well.  We leave digest and kx509
alone for the time being.

We also define the concept of kv-pairs in our audit trail which
allows us to define a rigorous but extensible format:

type error from-addr client server key1=val1 key2=val2 ...

kdc/kdc.h

@@ -101,18 +101,14 @@ typedef struct krb5_kdc_configuration {
     const char *app;
 } krb5_kdc_configuration;
 
+typedef struct kdc_request_desc *kdc_request_t;
+typedef struct astgs_request_desc *astgs_request_t;
+
 struct krb5_kdc_service {
     unsigned int flags;
 #define KS_KRB5		1
 #define KS_NO_LENGTH	2
-    krb5_error_code (*process)(krb5_context context,
-			       krb5_kdc_configuration *config,
-			       krb5_data *req_buffer,
-			       krb5_data *reply,
-			       const char *from,
-			       struct sockaddr *addr,
-			       int datagram_reply,
-			       int *claim);
+    krb5_error_code (*process)(kdc_request_t *, int *claim);
 };
 
 #include <kdc-protos.h>