Use internal implementation of internal Kerberos functions

Don't use KRB5_PRIVATE.

The patch implements and uses the following krb5 functions that are
otherwise private in recent MIT Kerberos releases:
 * krb5_principal2salt_norealm
 * krb5_free_ktypes

Signed-off-by: Simo Sorce <ssorce@redhat.com>

util/ipa_krb5.c

@@ -0,0 +1,44 @@
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include "ipa_krb5.h"
+
+void
+ipa_krb5_free_ktypes(krb5_context context, krb5_enctype *val)
+{
+    free(val);
+}
+
+/*
+ * Convert a krb5_principal into the default salt for that principal.
+ */
+krb5_error_code
+ipa_krb5_principal2salt_norealm(krb5_context context, krb5_const_principal pr, krb5_data *ret)
+{
+    unsigned int size = 0, offset=0;
+    krb5_int32 nelem;
+    register int i;
+
+    if (pr == NULL) {
+        ret->length = 0;
+        ret->data = NULL;
+        return 0;
+    }
+
+    nelem = krb5_princ_size(context, pr);
+
+    for (i = 0; i < (int) nelem; i++)
+        size += krb5_princ_component(context, pr, i)->length;
+
+    ret->length = size;
+    if (!(ret->data = malloc (size)))
+        return ENOMEM;
+
+    for (i = 0; i < (int) nelem; i++) {
+        memcpy(&ret->data[offset], krb5_princ_component(context, pr, i)->data,
+               krb5_princ_component(context, pr, i)->length);
+        offset += krb5_princ_component(context, pr, i)->length;
+    }
+    return 0;
+}

util/ipa_krb5.h

@@ -0,0 +1,12 @@
+#ifndef __IPA_KRB5_H_
+#define __IPA_KRB5_H_
+
+#include <krb5.h>
+
+void
+ipa_krb5_free_ktypes(krb5_context context, krb5_enctype *val);
+
+krb5_error_code
+ipa_krb5_principal2salt_norealm(krb5_context context, krb5_const_principal pr, krb5_data *ret);
+
+#endif /* __IPA_KRB5_H_ */