gss: expose gss_destroy_cred()

Build and export gss_destroy_cred(). This permanently destroys the credential,
rather than releasing a handle to it.

lib/gssapi/mech/gss_destroy_cred.c

@@ -29,8 +29,22 @@
 #include "mech_locl.h"
 #include <heim_threads.h>
 
-OM_uint32 GSSAPI_LIB_FUNCTION
-gss_destroy_cred(void *status,
+/**
+ * Destroy a credential 
+ *
+ * gss_release_cred() frees the memory, gss_destroy_cred() removes the credentials from memory/disk and then call gss_release_cred() on the credential.
+ *
+ * @param min_stat minor status code
+ * @param cred_handle credentail to destory
+ *
+ * @returns a gss_error code, see gss_display_status() about printing
+ *          the error code.
+ * 
+ * @ingroup gssapi
+ */
+
+GSSAPI_LIB_FUNCTION OM_uint32 GSSAPI_LIB_FUNCTION
+gss_destroy_cred(OM_uint32 *minor_status,
 		 gss_cred_id_t *cred_handle)
 {
     struct _gss_cred *cred;