parser CHANGE compile flag enabled_cache updated

Enables caching of some information, which
increases space complexity but improves time.
diff --git a/src/tree_data.h b/src/tree_data.h
index 9519108..fdf208a 100644
--- a/src/tree_data.h
+++ b/src/tree_data.h
@@ -18,6 +18,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "libyang.h"
 #include "tree_schema.h"
 #include "xml.h"