Remove unused declarations

src/hashtable.h

@@ -8,10 +8,6 @@
 #ifndef HASHTABLE_H
 #define HASHTABLE_H
 
-typedef size_t (*key_hash_fn)(const void *key);
-typedef int (*key_cmp_fn)(const void *key1, const void *key2);
-typedef void (*free_fn)(void *key);
-
 struct hashtable_list {
     struct hashtable_list *prev;
     struct hashtable_list *next;