Those functions are defined in hashtable_itr.c
I think this was made for "speed", but it break compilation with GCC-15
and is plainly unnecessary
--- a/util/hashtable_itr.h
+++ b/util/hashtable_itr.h
@@ -29,19 +29,13 @@
  * - return the value of the (key,value) pair at the current position */
 
-extern inline void *
-hashtable_iterator_key(struct hashtable_itr *i)
-{
-    return i->e->k;
-}
+extern void *
+hashtable_iterator_key(struct hashtable_itr *i);
 
 /*****************************************************************************/
 /* value - return the value of the (key,value) pair at the current position */
 
-extern inline void *
+extern void *
-hashtable_iterator_value(struct hashtable_itr *i)
-{
-    return i->e->v;
-}
+hashtable_iterator_value(struct hashtable_itr *i);
 
 /*****************************************************************************/
 /* advance - advance the iterator to the next element