Add function neu_datatag_tbl_size for getting tag count

include/neu_datatag_table.h

@@ -31,6 +31,7 @@ typedef struct neu_datatag_table neu_datatag_table_t;
 
 neu_datatag_table_t *neu_datatag_tbl_create(void);
 void                 neu_datatag_tbl_destroy(neu_datatag_table_t *);
+size_t               neu_datatag_tbl_size(neu_datatag_table_t *);
 neu_datatag_t *      neu_datatag_tbl_get(neu_datatag_table_t *, datatag_id_t);
 
 // We take ownership of the datatag, this implies that the datatag and the

src/base/neu_datatag_table.c

@@ -60,6 +60,11 @@ void neu_datatag_tbl_destroy(neu_datatag_table_t *tag_tbl)
     return;
 }
 
+size_t neu_datatag_tbl_size(neu_datatag_table_t *tbl)
+{
+    return tbl->datatag_table.id_count;
+}
+
 neu_datatag_t *neu_datatag_tbl_get(neu_datatag_table_t *tag_tbl,
                                    datatag_id_t         tag_id)
 {