Fixed: [Yang identityref XML encoding is not general](https://github.com/clicon/clixon/issues/90)

* Revisiting this issue now seems to work, there are no regressions that fail when disabling IDENTITYREF_KLUDGE.

lib/src/clixon_xpath_function.c

@@ -267,9 +267,7 @@ derived_from_one(char  *baseidentity,
     if (prefix == NULL)
         ymod = ys_module(yleaf);
     else{ /* from prefix to name */
-#if 1 /* IDENTITYREF_KLUDGE  */
         ymod = yang_find_module_by_prefix_yspec(ys_spec(yleaf), prefix);
-#endif
     }
     if (ymod == NULL)
         goto nomatch;