Initialize some data structure magic fields

Static analyzers may complain if they see a data structure copied with
an uninitialized field, even if the copy target won't use the field.
Add magic field initializers in three such places.

[ghudson@mit.edu: rewrote commit message]

src/lib/gssapi/krb5/util_cksum.c

@@ -48,6 +48,7 @@ kg_checksum_channel_bindings(context, cb, cksum)
 
     cksum->checksum_type = CKSUMTYPE_RSA_MD5;
     cksum->length = sumlen;
+    cksum->magic = KV5M_CHECKSUM;
 
     /* generate a buffer full of zeros if no cb specified */
 

src/lib/krb5/krb/authdata.c

@@ -976,9 +976,7 @@ krb5_authdata_export_internal(krb5_context kcontext,
 
     *ptr = NULL;
 
-    name.length = strlen(module_name);
-    name.data = (char *)module_name;
-
+    name = make_data((char *)module_name, strlen(module_name));
     module = k5_ad_find_module(kcontext, context, AD_USAGE_MASK, &name);
     if (module == NULL)
         return ENOENT;
@@ -1005,9 +1003,7 @@ krb5_authdata_free_internal(krb5_context kcontext,
     krb5_data name;
     struct _krb5_authdata_context_module *module;
 
-    name.length = strlen(module_name);
-    name.data = (char *)module_name;
-
+    name = make_data((char *)module_name, strlen(module_name));
     module = k5_ad_find_module(kcontext, context, AD_USAGE_MASK, &name);
     if (module == NULL)
         return ENOENT;