Abstract predicate and constant for unused hash keys

Qunbound is used for many things; using a predicate and constant for
the specific purpose of unused hash entry keys allows us to locate
them and make changes much more easily.

* src/lisp.h (HASH_UNUSED_ENTRY_KEY, hash_unused_entry_key_p):
New constant and function.
* src/comp.c (compile_function, Fcomp__compile_ctxt_to_file):
* src/composite.c (composition_gstring_cache_clear_font):
* src/emacs-module.c (module_global_reference_p):
* src/fns.c (make_hash_table, maybe_resize_hash_table, hash_put)
(hash_remove_from_table, hash_clear, sweep_weak_table, Fmaphash):
* src/json.c (lisp_to_json_nonscalar_1):
* src/minibuf.c (Ftry_completion, Fall_completions, Ftest_completion):
* src/print.c (print, print_object):
Use them.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/json.c b/src/json.c
index af5f30c7275..d98b312ecc9 100644
--- a/src/json.c
+++ b/src/json.c
@@ -364,7 +364,7 @@ lisp_to_json_nonscalar_1 (Lisp_Object lisp,
       for (ptrdiff_t i = 0; i < HASH_TABLE_SIZE (h); ++i)
         {
           Lisp_Object key = HASH_KEY (h, i);
-          if (!BASE_EQ (key, Qunbound))
+          if (!hash_unused_entry_key_p (key))
             {
               CHECK_STRING (key);
               Lisp_Object ekey = json_encode (key);