Add data_blob_string_const_null() function that includes the terminating

null byte and use it in Samba 3.

This matches the behaviour prior to my data_blob changes.

lib/util/data_blob.h

@@ -104,6 +104,14 @@ _PUBLIC_ char *data_blob_hex_string(TALLOC_CTX *mem_ctx, const DATA_BLOB *blob);
 **/
 _PUBLIC_ DATA_BLOB data_blob_string_const(const char *str);
 
+/**
+  useful for constructing data blobs in test suites, while
+  avoiding const warnings
+
+  includes the terminating null character (as opposed to data_blo_string_const)
+**/
+_PUBLIC_ DATA_BLOB data_blob_string_const_null(const char *str);
+
 /**
  * Create a new data blob from const data 
  */