libsepol/cil: Add cil_list_is_empty macro

Add a macro, called cil_list_is_empty, that returns true if the
list pointer or list head is NULL.

Signed-off-by: James Carter <jwcart2@gmail.com>
Reviewed-by: Daniel Burgener <dburgener@linux.microsoft.com>
Acked-by: Petr Lautrbach <lautrbach@redhat.com>

libsepol/cil/src/cil_list.h

@@ -44,6 +44,9 @@ struct cil_list_item {
 	void *data;
 };
 
+#define cil_list_is_empty(list) \
+	((list) == NULL || (list)->head == NULL)
+
 #define cil_list_for_each(item, list) \
 	for (item = (list)->head; item != NULL; item = item->next)